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賛成する

B1 verb #1,800 most common 12 min read

賛成する

sansei suru Top 1,800

At the A1 level, learners are just beginning to navigate basic Japanese conversations. While 賛成する (sansei suru) is technically a B1 word, beginners can start by learning the noun form '賛成' (sansei) as a simple, one-word response. When someone suggests a fun idea, like 'Let's eat sushi!' (Sushi o tabemashou!), an A1 learner can simply smile, nod, and say 'Sansei!' to mean 'I agree!' or 'Good idea!' This is much easier than trying to form complex sentences. At this stage, it is important to associate the word with positive feelings and agreement. You don't need to worry about the complex grammar or particles yet. Just knowing that 'Sansei' means 'Yes, let's do that' is a huge step in participating in group decisions. It acts as a fantastic vocabulary bridge, allowing beginners to show enthusiasm and alignment with their Japanese friends without needing extensive grammar knowledge. Practice saying 'Sansei desu' (I agree) to add a little politeness to your agreement.

As an A2 learner, you are starting to build simple sentences and understand basic grammar structures. Now is the perfect time to learn how to use 賛成する as a verb. The most important rule to master at this level is the particle に (ni). You must remember to say '[Noun] ni sansei shimasu'. For example, 'I agree with that idea' is 'Sono kangae ni sansei shimasu'. At the A2 level, you should practice using this pattern with common nouns like 意見 (iken - opinion), 考え (kangae - idea), and 計画 (keikaku - plan). You should also practice the past tense: '賛成しました' (sansei shimashita - I agreed) and the negative form: '賛成しません' (sansei shimasen - I do not agree). Be careful, though! In Japanese culture, saying 'I do not agree' directly can sound a bit strong. It is good to know the grammar, but in real life, Japanese people often use softer ways to disagree. Focus on using 賛成します to show your support for your friends' and colleagues' ideas.

At the B1 level, 賛成する becomes a core part of your active vocabulary. You are now expected to participate in discussions, express your opinions clearly, and respond to others' viewpoints. You should be completely comfortable with the '[Noun] + に + 賛成する' structure. Furthermore, you need to start distinguishing 賛成する from other similar words. You must understand that 賛成する is used for opinions and plans, not for facts. If someone says 'It is cold today,' you should not use 賛成する; you should use 'そうですね' (Sou desu ne). At this level, you can also start using adverbs to modify your agreement, such as '大賛成です' (daisansei desu - I strongly agree) or '全面的に賛成します' (zenmenteki ni sansei shimasu - I completely agree). You should also be able to understand relative clauses using this verb, such as '賛成する人' (sansei suru hito - people who agree). This word is essential for passing the JLPT N3 and for functioning in everyday Japanese society, from school debates to office meetings.

For B2 learners, the focus shifts to nuance, register, and complex sentence integration. You already know how to use 賛成する grammatically; now you must master its sociolinguistic applications. In business Japanese (Keigo), you need to know how to ask for agreement politely, such as 'ご賛成いただけますでしょうか' (Go-sansei itadakemasu deshou ka - Could I kindly receive your agreement?). You should also be comfortable reading news articles and understanding political contexts where '賛成派' (sansei-ha - the supporting faction) and '反対派' (hantai-ha - the opposing faction) are discussed. At the B2 level, you must flawlessly differentiate between 賛成する (supporting an idea), 同意する (giving formal consent), and 納得する (being convinced). You should be able to write essays arguing a point and stating '私はこの意見に賛成である' (Watashi wa kono iken ni sansei de aru) using the formal 'de aru' style. Understanding how to soften disagreement using phrases like '賛成しかねます' (sansei shikanemasu) is also crucial for maintaining professional relationships.

At the C1 level, your use of 賛成する should be near-native, characterized by a deep understanding of context and subtle emotional undertones. You are expected to engage in high-level debates, negotiations, and academic discussions. You should seamlessly incorporate idioms and advanced collocations, such as '賛成の意を表明する' (sansei no i o hyoumei suru - to express one's intention of agreement) or '満場一致で賛成する' (manjou itchi de sansei suru - to agree unanimously). You understand the cultural weight of 'nemawashi' (consensus building) and how securing 'sansei' behind the scenes is often more important than the formal vote. You can critically analyze texts where the author subtly manipulates the reader into a state of 'sansei'. Furthermore, you can articulate complex reasons for your agreement, using advanced grammar structures like '〜という点において賛成できる' (I can agree in the sense that...). Your vocabulary is broad enough that you rarely overuse 賛成する, opting instead for highly specific synonyms like 賛同 (sandou), 承諾 (shoudaku), or 迎合 (geigou - pandering/compromising agreement) depending on the exact rhetorical need.

At the C2 level, your mastery of 賛成する transcends grammar and vocabulary; it involves a profound comprehension of Japanese socio-linguistics, psychology, and historical context. You can dissect political discourse, understanding how politicians use the rhetoric of 'sansei' to build coalitions or alienate opponents. You are acutely aware of the philosophical implications of agreement in a collectivist society versus an individualist one. You can read classical or highly formal texts and understand archaic or highly specialized variations of agreement. You can play with the language, perhaps using 'sansei' ironically or in a double entendre. In negotiations, you know exactly how to withhold your 'sansei' to gain leverage, using the language of agreement and disagreement as a strategic tool. You can effortlessly switch between the most casual, slang-infused expressions of agreement among close friends to the most rigid, protocol-bound expressions required in diplomatic or high-level corporate environments. Your understanding of 賛成する is entirely holistic, reflecting a native-like intuition of the Japanese mind.

Practice it Examples Notes & Tips

賛成する in 30 Seconds

Means 'to agree' or 'to support' an idea.
Always uses the particle に (ni).
Used for opinions and plans, not facts.
Noun form '賛成' means 'agreement'.

The Japanese verb 賛成する (sansei suru) is a fundamental vocabulary word that translates primarily to 'to agree,' 'to approve,' or 'to support.' When you break down the kanji characters that make up this word, you gain a much deeper understanding of its core nuance and historical linguistic background. The first kanji, 賛 (san), carries the meaning of 'approve,' 'praise,' or 'assist.' It is often found in words related to support or endorsement. The second kanji, 成 (sei), means 'to become,' 'to turn into,' or 'to grow.' Together, they form a compound that literally implies assisting something to come into being or supporting an idea so that it can become a reality. This is why 賛成する is specifically used when you are agreeing with an opinion, a proposal, a plan, or an idea, rather than simply acknowledging a factual statement.

私はあなたの意見に賛成する。

Understanding this distinction is crucial for Japanese learners, as English speakers often use 'agree' in a much broader sense. For instance, if someone says 'It is raining outside,' you would not use 賛成する to agree with them, because the weather is a fact, not a proposal or an opinion.

Core Nuance: The word strongly implies an active endorsement of a subjective thought, plan, or direction, rather than passive acknowledgment of objective reality.

In Japanese society, where harmony (和 - wa) is highly valued, expressing agreement is a vital social skill. Using 賛成する appropriately shows that you are aligned with the group's direction or that you validate another person's perspective.

その計画に全面的に賛成する。

Furthermore, the word can function as a noun when the 'suru' is dropped. As a noun, 'sansei' means 'agreement' or 'approval.' You will often hear it in phrases like 'sansei desu' (I agree) or 'sansei no hito' (people who agree). It is also important to note the grammatical structure required when using this verb. The target of your agreement—the thing you are agreeing with—must be marked with the particle に (ni). You do not use the direct object particle を (o) with this verb.

Grammar Rule: Always use [Noun] + に + 賛成する. Never use [Noun] + を + 賛成する.

This particle usage highlights that your agreement is directed toward a specific point or proposal.

彼の提案に賛成する人は手を挙げてください。

As you progress in your Japanese studies, you will encounter various synonyms, but 賛成する remains the most versatile and universally understood term for expressing agreement with ideas. Mastering this word will significantly improve your ability to participate in discussions, share your viewpoints, and build consensus with Japanese speakers.

親は私の留学に賛成するだろうか。

By consistently practicing the [Noun] + に + 賛成する pattern, you will internalize the correct grammatical structure and avoid the common pitfall of translating directly from English.

Cultural Context: In Japan, expressing agreement is often accompanied by non-verbal cues such as nodding (aizuchi) to reinforce the verbal message of support.

Ultimately, 賛成する is an indispensable tool in your Japanese vocabulary arsenal, enabling clear, polite, and effective communication of your support for the ideas and proposals of others.

新しい法律に賛成する市民が多い。

Using 賛成する correctly in Japanese requires an understanding of both its grammatical requirements and its appropriate social contexts. As a suru-verb (Group 3), it is highly flexible and can be conjugated easily to fit various levels of politeness and tenses. The most critical grammatical rule to remember is the use of the particle に (ni). When you want to state what you are agreeing with, you must place に immediately after the noun representing the idea, opinion, or proposal.

私はその考えに賛成します。

This translates to 'I agree with that idea.' If you use the object particle を (o), the sentence will sound unnatural to native speakers.

Conjugation Basics: Present formal: 賛成します (sansei shimasu). Past formal: 賛成しました (sansei shimashita). Negative formal: 賛成しません (sansei shimasen).

In casual conversations with friends or family, you would use the dictionary form 賛成する (sansei suru) or the casual past form 賛成した (sansei shita). Often, in spoken Japanese, the 'suru' is dropped entirely, and people simply say '賛成！' (Sansei!) to mean 'I agree!' or 'I'm in!'

A: ピザを頼もう！ B: 賛成！

This standalone usage acts as an interjection of enthusiastic agreement. When you want to express strong agreement in a formal setting, you can use adverbs like 全面的に (zenmenteki ni - completely) or 大いに (ooi ni - highly/greatly) before the verb.

社長の意見に全面的に賛成します。

Conversely, if you disagree, you would use the negative form 賛成しない (sansei shinai) or 賛成しません (sansei shimasen). However, Japanese culture often favors indirectness to maintain harmony. Therefore, flatly saying '賛成しません' can sometimes sound too blunt or confrontational in delicate situations.

Softening Disagreement: Instead of a direct negative, Japanese speakers might say '賛成しかねます' (sansei shikanemasu - I find it difficult to agree) to soften the blow.

Another common usage pattern involves asking for someone else's agreement. You can ask '賛成ですか？' (Sansei desu ka? - Do you agree?) or '賛成してくれますか？' (Sansei shite kuremasu ka? - Will you agree/support me?).

この案に賛成する人はいますか？

It is also frequently used in relative clauses to describe people who hold a certain view, such as '賛成する人' (sansei suru hito - people who agree) or '賛成する意見' (sansei suru iken - agreeing opinions). Understanding these variations allows you to navigate both casual hangouts and formal boardroom meetings with ease. The verb is incredibly versatile, but its core function remains the same: to align yourself with a proposed thought, action, or philosophy.

Noun Modification: When modifying a noun, use the plain form: 賛成する理由 (sansei suru riyuu - the reason for agreeing).

By mastering the conjugation, the essential に particle, and the cultural nuances of direct versus indirect disagreement, you will be able to use 賛成する naturally and effectively in any Japanese conversation.

誰も私の意見に賛成してくれなかった。

The verb 賛成する (sansei suru) is ubiquitous in Japanese daily life, appearing in a wide array of contexts ranging from casual social gatherings to highly formal political arenas. Because expressing alignment and building consensus are core components of Japanese communication, you will encounter this word frequently. In the business world, it is a staple of meetings and negotiations. During a presentation or a strategy discussion, colleagues will use it to express their support for a proposed project or budget.

次回のプロジェクト案に賛成します。

In these corporate settings, the process of 'nemawashi' (informal consensus-building before a formal meeting) heavily relies on securing people's 賛成 (agreement) beforehand to ensure smooth decision-making.

Business Context: In formal meetings, you might hear 'ご賛成いただけますでしょうか' (Could I receive your approval?) as a highly polite request for agreement.

Beyond the boardroom, 賛成する is heavily used in politics and news media. When a new law is proposed in the Diet (the Japanese parliament), news anchors will report on the number of lawmakers who '賛成する' (support) or '反対する' (oppose) the bill.

多くの議員がその法案に賛成した。

Public opinion polls frequently ask citizens whether they agree or disagree with government policies, utilizing the noun form in options like '賛成' (Agree) and 'どちらかといえば賛成' (Somewhat agree). In educational settings, students are taught to use this word during debates and classroom discussions. A common classroom activity involves splitting students into a '賛成派' (agreeing side) and an '反対派' (opposing side) to discuss a specific topic.

私は制服を廃止することに賛成します。

On a more personal level, you will hear it constantly among friends and family when making plans. If someone suggests going to a specific restaurant or watching a certain movie, responding with a cheerful '大賛成！' (Daisansei! - I completely agree! / Great idea!) is a natural and enthusiastic way to show your support.

Casual Context: Friends often drop the 'suru' entirely. A simple '賛成！' is the equivalent of saying 'I'm down!' or 'Sounds good!' in English.

Furthermore, in online spaces like forums, social media, and comment sections, users frequently type '賛成' to express agreement with a post or opinion, similar to an upvote or a 'like.'

その意見には全く賛成できない。

You will also encounter it in literature and essays, where authors state their thesis and argue why readers should agree with their perspective. Because it bridges the gap between casual enthusiasm and formal endorsement, 賛成する is a word you will hear and read across all strata of Japanese society.

Media Context: Talk shows and panel discussions frequently feature guests stating '私は〇〇さんの意見に賛成です' to build upon another speaker's point.

Recognizing the context in which it is used will help you gauge the appropriate level of formality and the correct grammatical structure to apply when it is your turn to express agreement.

彼らは私の結婚に賛成してくれた。

While 賛成する (sansei suru) is a relatively straightforward word, English speakers and other learners often make specific grammatical and contextual mistakes due to direct translation habits. The most prevalent error is using the wrong particle. In English, we say 'I agree *with* the plan' or simply 'I agree.' This often leads learners to use the object particle を (o) or the accompaniment particle と (to).

❌ その計画を賛成する。 (Incorrect)

The correct particle is always に (ni), indicating the target or direction of your agreement.

Particle Error: Never use を (o) or と (to) with 賛成する. Always use に (ni). Think of it as directing your support 'toward' an idea.

Another major mistake stems from misunderstanding the scope of the word. In English, 'agree' is used for both opinions ('I agree we should go') and facts ('I agree that the sky is blue'). In Japanese, 賛成する is strictly reserved for opinions, proposals, plans, and subjective ideas.

❌ 今日は暑いということに賛成する。 (Incorrect usage for a fact)

If you want to agree with a factual statement or simply acknowledge that someone is correct, you should use expressions like 'その通りです' (sono toori desu - exactly / that's right) or '同感です' (doukan desu - I feel the same way). A third common mistake is overusing the negative form '賛成しません' (sansei shimasen) in professional or polite contexts. While grammatically correct, flatly stating 'I do not agree' can be perceived as overly aggressive or rude in Japanese culture, which values indirectness.

❌ 社長の意見には賛成しません。 (Too blunt for a boss)

Instead, native speakers often use softer expressions like '少し難しいと思います' (I think it might be a bit difficult) or '賛成しかねます' (I find it hard to agree).

Politeness Error: Avoid direct negation when disagreeing with superiors. Use softening phrases to maintain harmony.

Additionally, learners sometimes confuse 賛成する with 許可する (kyoka suru - to permit/allow). While a parent agreeing to let a child study abroad might feel like 'permission' in English, in Japanese, if the parent is supporting the child's *idea*, 賛成する is appropriate. If they are officially granting a right, 許可する is better.

⭕️ 父は私の計画に賛成してくれた。

Finally, remember that 賛成 is a noun and requires する to become a verb. Saying '私は賛成だ' (Watashi wa sansei da) is fine because you are using the noun with the copula 'da', but you cannot conjugate the noun itself like an i-adjective (e.g., ❌ 賛成くない is wrong; it must be 賛成じゃない). By paying close attention to the に particle, reserving the word for subjective proposals, softening your disagreements, and treating the word grammatically as a suru-verb, you will avoid the most common pitfalls and sound much more natural.

Summary of Fixes: Use に, apply only to opinions/plans, soften negatives, and conjugate as a Group 3 verb.

⭕️ その提案に賛成します。

The Japanese language offers several nuanced ways to express agreement, and understanding the subtle differences between 賛成する (sansei suru) and its synonyms will elevate your fluency. The most common synonym you will encounter is 同意する (doui suru). While both mean 'to agree,' their usage contexts differ slightly.

契約書に同意する。

賛成する is generally used when you support an opinion, a plan, or an idea—it carries a sense of active endorsement. 同意する, on the other hand, literally means 'same meaning' or 'same mind' and is often used for formal consent, such as agreeing to terms and conditions, signing a contract, or giving medical consent.

賛成 vs 同意: Use 賛成 for supporting ideas and proposals. Use 同意 for formal consent, contracts, and legal agreements.

Another related term is 賛同する (sandou suru). This word is very similar to 賛成する but is more formal and carries a stronger sense of active participation or backing. You might use 賛同する when you are not just agreeing with a charity's mission, but actively supporting it, perhaps financially or by joining their efforts.

彼の理念に賛同する。

If you want to express that you share the exact same feeling or sentiment as someone else, you would use 同感する (doukan suru) or the noun phrase 同感です (doukan desu). This is perfect for empathetic agreement. There is also 納得する (nattoku suru), which means to consent or agree after understanding the reasoning. It translates closer to 'to be convinced' or 'to accept.' You use this when someone explains a complex situation to you, and you finally see their point and agree with their logic.

説明を聞いて納得した。

For acknowledging factual statements, as mentioned in the common mistakes section, you should avoid 賛成する and instead use phrases like その通りです (sono toori desu - exactly / that is right).

Factual Agreement: For facts, use その通り (sono toori) or 本当ですね (hontou desu ne). Never use 賛成.

In highly formal business or legal contexts, you might also encounter 承諾する (shoudaku suru), which means to accept or consent to a request or demand. This is heavier than 賛成する and implies taking on a responsibility based on the agreement.

条件を承諾する。

By categorizing these words based on their specific use cases—賛成 for ideas, 同意 for consent, 同感 for feelings, 納得 for understanding, and 承諾 for formal acceptance—you can express your agreement with native-like precision.

Quick Reference: 賛成 = Support idea. 同意 = Formal consent. 同感 = Shared feeling. 納得 = Convinced.

みんながそのアイデアに賛成した。

How Formal Is It?

Formal

Difficulty Rating

Grammar to Know

Examples by Level

A: ピザを食べよう！ B: 賛成！

A: Let's eat pizza! B: I agree! (Good idea!)

Used as a standalone noun for enthusiastic agreement.

私は賛成です。

I agree.

Noun + です (desu) for polite agreement.

大賛成！

I completely agree! / Great idea!

大 (dai - big) + 賛成 (sansei) = strong agreement.

賛成ですか？

Do you agree?

Adding か (ka) to make it a question.

はい、賛成です。

Yes, I agree.

Basic polite affirmation.

みんな賛成です。

Everyone agrees.

みんな (minna) means everyone.

A: 映画を見よう。 B: 賛成！

A: Let's watch a movie. B: I agree!

Casual conversational response.

賛成の人は？

Who agrees? (People who agree?)

賛成の人 (sansei no hito) means 'people who agree'.

私はその意見に賛成します。

I agree with that opinion.

Noun + に (ni) + 賛成します (sansei shimasu).

彼の考えに賛成しました。

I agreed with his idea.

Past tense: 賛成しました (sansei shimashita).

この計画に賛成ですか？

Do you agree with this plan?

Question form in polite Japanese.

私は賛成しません。

I do not agree.

Negative form: 賛成しません (sansei shimasen).

母は私の留学に賛成した。

My mother agreed to my studying abroad.

Casual past tense: 賛成した (sansei shita).

誰も賛成しませんでした。

No one agreed.

誰も (daremo - no one) + negative past.

友達の提案に賛成する。

I agree with my friend's proposal.

Dictionary form used in casual speech or writing.

賛成する人は手を挙げてください。

Those who agree, please raise your hand.

Modifying a noun: 賛成する人 (sansei suru hito).

新しいルールに全面的に賛成します。

I completely agree with the new rule.

全面的に (zenmenteki ni) means 'completely' or 'fully'.

彼の意見には賛成できない。

I cannot agree with his opinion.

Potential negative form: 賛成できない (sansei dekinai).

会議で多くの人がその案に賛成した。

Many people agreed with the proposal at the meeting.

Using 案 (an - proposal) with the に particle.

賛成か反対か、意見を言ってください。

Please state your opinion, whether you agree or disagree.

賛成か反対か (sansei ka hantai ka) - agree or disagree.

親に賛成してもらうために、説明しました。

I explained it in order to get my parents to agree.

賛成してもらう (sansei shite morau) - to receive agreement.

環境保護の活動に賛成しています。

I am in agreement with (support) environmental protection activities.

State of agreeing: 賛成している (sansei shite iru).

その考えに賛成する理由は何ですか？

What is the reason you agree with that idea?

Modifying 理由 (riyuu - reason).

条件付きで賛成します。

I agree on certain conditions.

条件付きで (joukentsuki de) - with conditions.

法案は賛成多数で可決された。

The bill was passed by a majority vote (majority agreement).

賛成多数 (sansei tasuu) - majority in favor.

誠に遺憾ながら、そのご提案には賛成しかねます。

I regret to say that I find it difficult to agree with your proposal.

〜しかねる (shikaneru) - polite way to say 'cannot do'.

彼の主張の意図は理解できるが、賛成はできない。

I can understand the intent of his argument, but I cannot agree with it.

Contrastive use of は (wa) with 賛成.

住民の多くが建設プロジェクトに賛成の意を示した。

Many residents showed their intention to agree with the construction project.

賛成の意を示す (sansei no i o shimesu) - to show intention of agreement.

野党はその政策に断固として賛成しない姿勢を貫いた。

The opposition party maintained a firm stance of not agreeing with the policy.

断固として (danko to shite) - firmly / resolutely.

満場一致で賛成となりました。

It was agreed upon unanimously.

満場一致で (manjou itchi de) - unanimously.

賛成派と反対派の間で激しい議論が交わされた。

A heated debate took place between the supporting and opposing factions.

賛成派 (sansei-ha) - supporting faction/group.

上司の意見に無条件で賛成するのは危険だ。

It is dangerous to agree unconditionally with your boss's opinion.

無条件で (mujouken de) - unconditionally.

本会議において、当該議案に賛成の票を投じた。

At the plenary session, I cast a vote in favor of the said bill.

賛成の票を投じる (sansei no hyou o toujiru) - to cast a vote in favor.

彼の意見には首肯できる点も多いが、全面的に賛成するには至らない。

There are many points in his opinion that I can nod to, but it doesn't go so far as me completely agreeing.

〜には至らない (ni wa itaranai) - does not reach the point of...

世論調査によれば、制度改革への賛成論が過半数を占めている。

According to the public opinion poll, arguments in favor of the system reform account for the majority.

賛成論 (sanseiron) - argument in favor.

事前の根回しが功を奏し、役員会でスムーズに賛成を取り付けた。

The prior behind-the-scenes consensus building paid off, and we smoothly secured agreement at the board meeting.

賛成を取り付ける (sansei o toritsukeru) - to secure/obtain agreement.

倫理的な観点から、その研究手法には到底賛成しがたい。

From an ethical standpoint, it is absolutely difficult to agree with that research method.

到底〜しがたい (toutei ~ shigatai) - absolutely difficult to...

両国は共同声明を発表し、平和維持活動への賛成の立場を明確にした。

The two countries issued a joint statement, clarifying their stance of agreement towards peacekeeping operations.

賛成の立場 (sansei no tachiba) - stance of agreement.

一部の熱狂的な支持者を除き、その過激な思想に賛成する者は皆無であった。

Except for a few fanatical supporters, there was absolutely no one who agreed with that radical ideology.

皆無である (kaimu de aru) - to be non-existent / none at all.

賛成の意を込めて、深く頷いた。

I nodded deeply, embedding my intention of agreement.

〜の意を込めて (~ no i o komete) - with the intention of...

表面上は賛成を装いつつも、裏では巧妙に計画の頓挫を画策していた。

While feigning agreement on the surface, behind the scenes they were cleverly scheming the collapse of the plan.

賛成を装う (sansei o yosoou) - to feign agreement.

その妥協案は、各派閥の思惑が交錯する中で、消極的賛成を得るにとどまった。

Amidst the intersecting ulterior motives of each faction, the compromise plan only managed to gain passive agreement.

消極的賛成 (shoukyokuteki sansei) - passive/reluctant agreement.

時代の趨勢を鑑みれば、この変革に賛成せざるを得ないというのが偽らざる心境だ。

Considering the trend of the times, my genuine feeling is that I have no choice but to agree with this transformation.

賛成せざるを得ない (sansei sezaru o enai) - cannot help but agree / forced to agree.

彼の演説は聴衆の情に訴えかけ、理屈を超えた次元で賛成のうねりを巻き起こした。

His speech appealed to the emotions of the audience, whipping up a surge of agreement on a level beyond logic.

賛成のうねり (sansei no uneri) - a surge/wave of agreement.

総論賛成・各論反対という、日本特有の意思決定のジレンマに陥っている。

We have fallen into the dilemma of decision-making peculiar to Japan: agreeing with the general theory but opposing the specific details.

総論賛成・各論反対 (souron sansei, kakuron hantai) - agreeing in principle but disagreeing on the details.

既得権益層からの猛反発が予想される中、あえて賛成の旗幟を鮮明にした。

While fierce backlash from vested interests was expected, they daringly made their banner of agreement clear.

賛成の旗幟を鮮明にする (sansei no kishi o senmei ni suru) - to make one's stance of agreement clear.

暗黙の了解のもと、異議を唱えることなく追従的賛成に終始した。

Under a tacit understanding, they remained in a state of sycophantic agreement from beginning to end without raising any objections.

追従的賛成 (tsuijuuteki sansei) - sycophantic/blind agreement.

多様な価値観が並存する現代社会において、全会一致の賛成を求めること自体が幻想に過ぎない。

In modern society where diverse values coexist, seeking unanimous agreement is itself nothing more than an illusion.

全会一致の賛成 (zenkai itchi no sansei) - unanimous agreement.

Common Collocations

意見に賛成する

計画に賛成する

提案に賛成する

全面的に賛成する

大賛成する

賛成多数

賛成派

賛成の意を表す

賛成の票を投じる

賛成を取り付ける

Common Phrases

大賛成です

賛成しかねます

賛成の人は手を挙げてください

賛成か反対か

私は賛成です

条件付きで賛成する

満場一致で賛成する

賛成に回る

賛成を求める

賛成の立場をとる

Often Confused With

賛成する vs 同意する (doui suru) - Used more for formal, legal, or medical consent.

賛成する vs 納得する (nattoku suru) - Used when you are convinced of something after an explanation.

賛成する vs 同感する (doukan suru) - Used when you share the exact same feeling or emotion.

Idioms & Expressions

Easily Confused

賛成する vs

Sentence Patterns

How to Use It

nuance

Implies a subjective alignment of thought. It is an active choice to support something, not just a passive realization of truth.

formality

Highly versatile. Can be used in the most casual slang ('Sansei!') to highly formal business ('Go-sansei itashimasu').

common error

Using it for facts. Do not say 'It is raining, I agree (sansei)'. Say 'Sou desu ne' instead.

Common Mistakes

Using を (o) instead of に (ni). (e.g., ❌ 案を賛成する ⭕️ 案に賛成する)
Using 賛成する to agree with a factual statement. (e.g., ❌ 地球が丸いことに賛成する ⭕️ 地球が丸いというのはその通りだ)
Conjugating the noun form like an adjective. (e.g., ❌ 賛成くない ⭕️ 賛成じゃない / 賛成しない)
Being too direct with the negative form in business. (e.g., ❌ 社長に賛成しません ⭕️ 社長のご意見には賛成しかねます)
Confusing it with 許可する (to permit) when talking about authority figures allowing actions.

Tips

Always use に (ni)

The most important grammatical rule for this word is the particle. Always link the idea you are agreeing with using に. Example: 計画に賛成する (Agree with the plan).

Casual 'Sansei!'

In casual conversations with friends, you don't need the 'suru'. Just shouting '賛成！' (Sansei!) is the perfect way to say 'I'm in!' or 'Great idea!'

The Art of Nemawashi

In Japanese business, getting 'sansei' often happens before the actual meeting. This behind-the-scenes consensus building is called 'nemawashi' and is crucial for success.

Opinions vs. Facts

Remember that 賛成 is for subjective ideas, not objective facts. You agree with a *plan* to go to the park, but you don't agree with the *fact* that the park has trees.

Softening Disagreement

Avoid flatly saying '賛成しません' to your boss. Use '賛成しかねます' (sansei shikanemasu) to sound professional, polite, and culturally appropriate.

Add 'Dai' for Emphasis

Want to sound super enthusiastic? Add 大 (dai) to the front. '大賛成' (Daisansei) means 'I completely, 100% agree with you!'

Use 'Ha' for Groups

When talking about debates or politics, use 賛成派 (sansei-ha) to describe the 'pro' side or the supporting faction.

Consent vs. Agreement

If you are signing a contract or giving medical permission, switch to 同意する (doui suru). Save 賛成 for ideas and proposals.

Listen for Tasuu

In the news, '賛成多数' (sansei tasuu) means a bill passed by majority vote. It's a very common collocation in political reporting.

Formal Essays

When writing a formal essay or thesis, use '私は〜に賛成である' (Watashi wa ~ ni sansei de aru) to state your position clearly and academically.

Memorize It

Mnemonic

Imagine the SUN (賛 - san) SAYing (成 - sei) 'I agree!' to make the plants GROW (become/成).

Word Origin

Cultural Context

Saying '賛成です' is almost always accompanied by a deep nod (unazuki). Continuous small nods (aizuchi) while someone is speaking also signal that you are leaning towards 'sansei'.

Directly saying '賛成しません' (I disagree) to a superior is often considered too blunt. Japanese speakers prefer softening phrases like '少し難しいですね' (It's a bit difficult) or '賛成しかねます' (I find it hard to agree).

Practice in Real Life

Real-World Contexts

Conversation Starters

"この新しいルールについて、賛成ですか？ (Do you agree with this new rule?)"

"私のアイデアに賛成してくれますか？ (Will you support my idea?)"

"みんなが賛成するなら、そうしましょう。 (If everyone agrees, let's do that.)"

"正直に言うと、その案には賛成できません。 (To be honest, I cannot agree with that proposal.)"

"大賛成！いつから始めますか？ (I completely agree! When do we start?)"

Journal Prompts

最近、ニュースで見て賛成した意見は何ですか？ (What is an opinion you saw in the news recently that you agreed with?)

友達の計画に賛成できなかった時のことを書いてください。 (Write about a time you couldn't agree with a friend's plan.)

「制服をなくす」という意見に賛成ですか、反対ですか？理由も書いてください。 (Do you agree or disagree with the idea of abolishing school uniforms? Write the reason too.)

日本の「根回し」という文化に賛成ですか？ (Do you agree with the Japanese culture of 'nemawashi'?)

絶対に賛成できないルールは何ですか？ (What is a rule you can absolutely never agree with?)

Frequently Asked Questions

10 questions

No, you should never use the object particle を (o) with 賛成する. The correct particle is always に (ni). Think of your agreement as an arrow pointing *toward* an idea. Therefore, you say '意見に賛成する' (iken ni sansei suru), not '意見を賛成する'.

While both mean 'to agree', 賛成する is used when you support an opinion, idea, or plan. It has a feeling of active endorsement. 同意する (doui suru) is used more for formal consent, such as agreeing to terms of service, signing a contract, or giving medical consent.

The most natural way to say 'I strongly agree' or 'I completely agree' is to use the prefix 大 (dai - big/great) and say '大賛成です' (daisansei desu). In formal contexts, you can use the adverb 全面的に (zenmenteki ni - completely) and say '全面的に賛成します'.

Grammatically, it is correct, but in Japanese culture, direct disagreement can be perceived as blunt or confrontational, especially with superiors. It is often better to use softer expressions like '賛成しかねます' (I find it difficult to agree) or '少し違うと思います' (I think it's a little different).

No, this is a common mistake. 賛成する is only used for subjective opinions, proposals, or plans. If someone states a fact like 'Tokyo is a big city', you should not say '賛成します'. Instead, use 'その通りですね' (That's exactly right) or 'そうですね' (That is so).

In polite Japanese, you can simply ask '賛成ですか？' (Sansei desu ka?). If you are asking a group, you might say '賛成の人はいますか？' (Are there people who agree?). In a formal business setting, you would ask 'ご賛成いただけますでしょうか' (Could I receive your agreement?).

The suffix 派 (ha) means 'faction' or 'group'. Therefore, 賛成派 (sansei-ha) refers to the group of people who support a specific idea, policy, or plan. You will often hear this in news reports contrasting the 賛成派 with the 反対派 (hantai-ha - opposing faction).

Yes, absolutely. 賛成 is a noun meaning 'agreement' or 'approval'. You can use it with the copula 'desu' (賛成です - I agree / It is an agreement) or modify it with other nouns (賛成の意見 - an agreeing opinion).

The direct antonym is 反対する (hantai suru), which means 'to oppose' or 'to disagree'. Just like 賛成する, it also takes the particle に (ni). For example, 'その案に反対する' (I oppose that plan).

The phrase for 'unanimous agreement' is 満場一致 (manjou itchi). To say 'agreed unanimously', you would say '満場一致で賛成した' (manjou itchi de sansei shita). This is a very useful phrase for business and formal meetings.

Test Yourself 200 questions

writing

Translate: 'I agree with that plan.'

Well written! Good try! Check the sample answer below.

Use [Noun] + に + 賛成します。