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Vocabulary
確信する

B1 verb 10 min read

確信する

kakushin suru

Practice it Examples Notes & Tips 確信する in 30 Seconds

Explanation 確信する in your Level:

At the A1 level, you usually learn simple ways to say 'I think' (omou) or 'I believe' (shinjiru). 'Kakushin suru' is a bit more advanced, but you can understand it as a very strong 'I am sure.' Imagine you are 100% sure about something. Instead of just saying 'maybe' or 'I think,' you use this word to show you have no doubts. For example, if you see your friend practicing very hard, you might say 'I am sure you will win.' In Japanese, that 'I am sure' feeling is what 'kakushin suru' is all about. It's like having a solid rock of belief in your heart. Even beginners can use it if they want to sound very confident about a simple fact, like 'I am sure this is my bag.' However, usually, beginners use 'zettai' (absolutely) to show this feeling. Learning 'kakushin suru' early helps you recognize it in anime or movies when a hero is very confident. It's a 'suru' verb, so you use it like 'kakushin shimasu.'

At the A2 level, you are starting to connect sentences and express more complex feelings. 'Kakushin suru' becomes useful when you want to distinguish between a guess and a firm belief. You might have learned 'tabun' (probably) or 'kamoshirenai' (might). 'Kakushin suru' is the opposite of those. It means you have looked at the situation and made a final decision in your mind. For example, 'I am convinced that he is a good person' (Kare wa ii hito da to kakushin shite imasu). At this level, you should focus on the pattern '~to kakushin shite imasu.' This is the most common way to use it in daily life. It helps you sound more mature and decisive. You will also start to see it in simple news stories or reading passages about people's goals. If a character in a story is working toward a dream, they might 'kakushin' that their hard work will pay off. It is a step up from just 'thinking' something is true.

B1 is the level where 'kakushin suru' truly belongs. At this stage, you are expected to handle more abstract topics and express your opinions with nuance. 'Kakushin suru' allows you to show deep conviction. It is often used in business contexts or academic discussions to present a conclusion. For example, when discussing a project, you might say, 'I am convinced this plan is the best' (Kono puran ga saizen da to kakushin shite imasu). You should also learn the noun form 'kakushin' and phrases like 'kakushin wo motsu' (to have conviction). At B1, you are learning to provide reasons for your thoughts. 'Kakushin suru' implies that you have those reasons. It’s not just a blind belief; it’s a reasoned certainty. You will hear this word in interviews, documentaries, and more formal social settings. It helps you bridge the gap between simple conversation and professional Japanese. You should also be careful not to use it for things that are just 'likely'—save it for when you are truly convinced.

At the B2 level, you should be able to use 'kakushin suru' fluently in various registers. You will notice it appearing in literature and complex news reports. At this level, you should understand the subtle difference between 'kakushin suru' and its synonyms like 'dangen suru' (to assert) or 'shinjite utagawanai' (to believe without doubt). You might use it to describe a psychological state: 'Having seen the evidence, I reached a state of conviction' (Shouko wo mite, kakushin ni itatta). You should also be comfortable using the humble form 'kakushin shite orimasu' in business emails or formal presentations. This shows a high level of linguistic competence and cultural awareness. You can also use it to discuss social issues or scientific theories where certainty is a key theme. At B2, you are not just learning the word; you are learning the weight it carries in a conversation and how it affects the listener's perception of your confidence and reliability.

At the C1 level, you explore the philosophical and rhetorical uses of 'kakushin suru.' It is used to build strong arguments in essays or debates. You might analyze how a writer uses 'kakushin' to persuade the reader or to characterize a protagonist's unwavering resolve. You should be able to use the word in complex grammatical structures, such as 'kakushin suru ni ataru' (worth being convinced of) or 'kakushin wo fukameru' (to deepen one's conviction). You will also encounter it in historical contexts, such as leaders expressing their 'kakushin' in a particular ideology or course of action. At this level, you understand that 'kakushin' is a subjective certainty that the speaker presents as an objective truth. You can use it to critique arguments, noting when someone's 'kakushin' lacks sufficient evidence. Your vocabulary should now include related idiomatic expressions and the ability to switch between 'kakushin suru' and more literary terms like 'shinnen' (conviction/belief).

At the C2 level, you possess a native-like grasp of 'kakushin suru.' You understand its role in the 'logic of conviction' within Japanese discourse. You can use it to express the finest shades of certainty, perhaps using it ironically or to highlight the danger of over-certainty in a philosophical discussion. You are familiar with its usage in classical or high-level modern literature, where 'kakushin' might be contrasted with 'fuan' (anxiety) or 'kaigi' (skepticism). You can engage in high-level debates about topics like 'The certainty of scientific knowledge' (Kagakuteki chishiki no kakushin-sei). You also understand how the word interacts with Japanese social dynamics—how a senior leader's 'kakushin' can influence an entire organization's direction. Your use of the word is perfectly timed and carries the appropriate emotional and intellectual weight. You can effortlessly substitute it with extremely formal or archaic synonyms in specific contexts, demonstrating a deep mastery of the Japanese language's expressive range.

Practice it Examples Notes & Tips

確信する in 30 Seconds

To be absolutely certain or convinced.
Stronger than 'think' or 'believe.'
Used in formal, business, and dramatic contexts.
Implies a state of mind without doubt.

The Japanese verb 確信する (kakushin suru) is a powerful and assertive expression used to convey a state of absolute certainty or deep conviction. At its core, it is composed of two kanji characters: 確 (kaku), which means 'certain,' 'tight,' or 'solid,' and 信 (shin), which means 'trust,' 'faith,' or 'belief.' When combined with the functional verb する (suru), it transforms into an action or state of 'having firm belief' or 'being convinced.' Unlike the simpler verb 思う (omou - to think) or even 信じる (shinjiru - to believe), 確信する implies that all doubt has been removed from the mind of the speaker. It is not merely a guess or a hopeful thought; it is a psychological state where the individual feels they have sufficient evidence or an unshakable internal feeling that something is true or will happen.

Semantic Depth: The word captures a transition from uncertainty to a solid conclusion. It is often used in moments of realization or after evaluating a situation thoroughly.

In social contexts, using 確信する carries a heavy weight. If you tell someone you 'kakushin shite iru' regarding their success, you are offering much more than a polite encouragement; you are stating that, in your view, their success is already a factual reality that has yet to manifest. This makes it a common fixture in professional settings, sports interviews, and dramatic narratives.

最新のデータを見て、私はこのプロジェクトが成功すると確信するに至りました。

Culturally, Japanese communication often favors ambiguity to avoid conflict, but 確信する is a notable exception. It is used when a speaker wants to take a definitive stand. For instance, a detective in a mystery novel might say they 'kakushin' the identity of the culprit once the final piece of the puzzle falls into place. It signifies the end of an investigation or a period of questioning.

Syntactic Flexibility: It can be used with the particle 'wo' to indicate the object of certainty (e.g., shouri wo kakushin suru - to be sure of victory) or with the particle 'to' to introduce a clause (e.g., kare ga kuru to kakushin suru - to be sure that he will come).

Furthermore, the word appears frequently in written Japanese, such as in editorials, academic papers, and formal reports, where the author presents a conclusion based on rigorous analysis. It bridges the gap between subjective feeling and objective evidence. When you use this word, you are signaling to your audience that your mind is made up and you are ready to act upon that certainty.

彼女の目を見た瞬間、彼は彼女が嘘をついていないことを確信した。

Register and Tone: While not overly stiff, it is more formal than 'zettai da to omou.' It suggests a level of maturity and intellectual rigor in one's thought process.

我々は、この技術が未来を変えると確信しています。

Grammatically, 確信する (kakushin suru) functions as a transitive verb that can take several types of complements. The most common structure involves the particle を (wo) to mark a noun that represents the thing you are certain about. For example, 'shouri wo kakushin suru' (to be certain of victory) or 'seikou wo kakushin suru' (to be certain of success). This usage is direct and highlights the target of the conviction.

The Clause Pattern: Another frequent pattern is [Sentence in Plain Form] + と確信する. This allows you to express certainty about a full thought or event. For example, 'Kare wa hannin dewa nai to kakushin shite iru' (I am convinced that he is not the culprit).

This 'to' particle functions as a quotation or thought marker, linking the specific belief to the verb of conviction. When using this pattern, the verb is often in the ~te iru form (kakushin shite iru) because conviction is usually a continuous state of mind rather than a momentary action.

証拠が不十分であっても、私は彼の無実を確信している。

In formal writing or speeches, you might see the noun form 確信 (kakushin) used with the verb 'motsu' (to have), as in 'kakushin wo motsu' (to have conviction/certainty). This emphasizes the possession of the feeling. Additionally, you can use 'kakushin ni michiru' to describe someone who is 'overflowing with confidence' or 'full of conviction.'

Tense and Aspect: Using the past tense 'kakushin shita' usually refers to the specific moment when you became convinced. 'Kakushin shite ita' suggests you were convinced in the past, perhaps implying that the situation has since changed or been confirmed.

その知らせを聞いた時、私はすべてがうまくいったと確信した。

Negative forms like 'kakushin dekinai' (cannot be certain) are also common, especially in scientific or investigative contexts where evidence is lacking. 'Kakushin ga nai' (there is no certainty) is the noun-based equivalent.

Adverbial Support: Words like 'tsuyoku' (strongly) or 'kataku' (firmly) often precede the verb to intensify the level of conviction: 'Tsuyoku kakushin shite iru.'

彼は自分の直感が正しいことを強く確信しているようだ。

この新製品が市場で高く評価されることを確信しております。

Causative and Passive: While less common, 'kakushin saseru' (to make someone convinced) can be used when evidence or an event forces a conclusion upon someone else.

You will encounter 確信する in a variety of high-stakes environments. One of the most prominent places is in the world of sports and competition. After a major victory or even during the middle of a game, athletes and coaches are frequently asked about their mindset. A coach might say, 'During the third quarter, I was convinced of our victory' (Daisan kuootaa de shouri wo kakushin shimashita). This usage highlights the psychological turning point in a competitive struggle.

News and Media: News anchors and journalists use this word when reporting on political movements or economic shifts. For example, 'Analysts are convinced that interest rates will rise' (Anarisuto wa kinri ga agaru to kakushin shite iru).

In the legal and crime genre of Japanese media—such as the popular 'Detective Conan' or 'Ace Attorney' series—this word is a staple. Detectives use it when they find the 'smoking gun' or the 'decisive evidence' (ketteiteki na shouko). It marks the transition from 'utagau' (suspecting) to 'kakushin suru' (being certain).

犯人がこの中にいると、私は確信しました。

In the world of science and academia, 確信する is used when a hypothesis is supported by overwhelming data. While scientists are generally cautious, they use this term when a theory has moved beyond mere speculation. You might hear it in documentaries or read it in scientific journals when discussing breakthroughs.

Daily Life and Relationships: In more personal contexts, it’s used to express deep trust. A person might say they 'kakushin' their partner's loyalty. It’s a way to say, 'I don't just think you're loyal; I know it in my heart.'

君なら絶対にできると、僕は確信しているよ。

Literature also makes heavy use of this word to describe internal monologues. Authors use it to show a character's resolve or a sudden epiphany. When a protagonist decides to embark on a dangerous journey, they often 'kakushin' that it is the only path forward.

Self-Reflective Use: People use it to describe their own growth, such as 'I am convinced that my efforts were not in vain' (Doryoku wa muda dewa nakatta to kakushin shite iru).

この経験が将来役に立つと、私は確信しています。

One of the most frequent mistakes learners make is confusing 確信する (kakushin suru) with 信じる (shinjiru). While both involve belief, 'shinjiru' is more about faith and emotional trust, often without needing proof. In contrast, 'kakushin suru' implies a conclusion reached through logic, evidence, or a very strong intuitive realization that feels like fact. Using 'shinjiru' when you mean you are '100% certain of a fact' can make you sound less confident than you intend.

The 'Omou' Trap: Another mistake is overusing 'omou' (to think) in situations that require more weight. If you are reporting to your boss about a project's success, saying 'seikou suru to omoimasu' sounds like a mere opinion. Saying 'seikou wo kakushin shite orimasu' shows professional conviction and responsibility.

Another error involves the particle choice. Learners sometimes use 'ni' instead of 'wo' or 'to.' While 'kakushin ni michiru' (to be full of conviction) uses 'ni,' the direct object of your certainty must be 'wo' or the clause marker 'to.' For example, 'shouri ni kakushin suru' is incorrect; it should be 'shouri wo kakushin suru.'

× 彼の成功に確信している。
○ 彼の成功を確信している。

There is also the issue of over-assertiveness. In Japanese culture, being too certain can sometimes come across as arrogant or inflexible. If you 'kakushin' something that turns out to be wrong, you may lose more face than if you had used a softer expression. Use it when you are prepared to stand by your statement.

Misusing the Tense: Learners often forget to use the '~te iru' form. Saying 'kakushin suru' sounds like you are making the decision to be certain right at this second. 'Kakushin shite iru' is almost always the correct way to describe your ongoing state of certainty.

× 私は今、勝利を確信する。
○ 私は今、勝利を確信している。

Finally, remember that 確信する is a 'suru' verb. Forgetting the 'suru' and just saying 'kakushin' makes it a noun, which requires a different sentence structure (like 'kakushin ga aru').

Contextual Appropriateness: Using this word for something that is already a known fact (like 'I am certain 1+1=2') is strange. It is best reserved for predictions, judgments, or beliefs about subjective truths.

To truly master 確信する (kakushin suru), it’s helpful to understand the nuances of its synonyms and related terms. The most direct alternative is probably 確信を持つ (kakushin wo motsu), which means 'to have conviction.' This is slightly more noun-focused and can sound a bit more formal or deliberate.

Comparison: 信じて疑わない: 'Shinjite utagawanai' literally means 'to believe and not doubt.' This is much more emotional and personal than 'kakushin suru.' It is often used for faith in people or long-held beliefs, whereas 'kakushin suru' is often based on situational evidence.

Another related word is 断言する (dangen suru), which means 'to assert' or 'to state positively.' While 'kakushin suru' describes an internal state of mind, 'dangen suru' describes the act of speaking that certainty aloud to others. You 'kakushin' in your head, and then you might 'dangen' it to an audience.

彼はその計画が失敗すると断言した。

Then there is 思い込む (omoikomu), which means 'to be under the impression' or 'to convince oneself.' This often has a negative connotation, suggesting that the person is certain about something that is actually false or that they haven't considered other possibilities. 'Kakushin suru' is generally more neutral or positive.

Comparison: 確証を得る: 'Kakushou wo eru' means 'to obtain corroborating evidence.' This is the process that often leads to 'kakushin suru.' You get the proof (kakushou) and then you become convinced (kakushin).

For a more casual way to say you are sure, people often use 'zettai' (absolutely) with 'da' or 'omou.' For example, 'Zettai ni dekiru to omou' is the everyday version of 'Dekiru to kakushin shite iru.'

私は絶対に彼が勝つと思う。

Comparison: 見極める: 'Mikiwameru' means 'to see through' or 'to ascertain.' It describes the analytical process of looking at something until the truth becomes clear, which is the precursor to 'kakushin suru.'

事の真相を見極めることが重要だ。

How Formal Is It?

Fun Fact

The kanji 確 was originally used to describe the hardness of rocks or the certainty of a physical structure. Today, it describes the 'hardness' of a thought.

Pronunciation Guide

UK /kakuɕin suɾu/

US /kɑːkuːʃiːn suːruː/

Pitch accent: kakushin (Low-High-High-High)

Rhymes With

Shinjiru (to believe) Anshin (peace of mind) Kanshin (interest) Zenshin (progress) Kesshin (determination) Shoushin (heartbreak) Youshin (caution) Tokushin (consent)

Common Errors

Pronouncing 'shin' like the English 'sin.' It should be 'sheen' but short.
Over-stressing the 'u' at the end of 'suru.'

Difficulty Rating

Reading 3/5

The kanji are common but require B1 level knowledge. Recognition is usually easy.

Writing 4/5

Writing the kanji 'kaku' (確) can be tricky due to the number of strokes.

Speaking 3/5

Easy to conjugate as a suru-verb, but requires confidence in tone.

Listening 2/5

Clearly pronounced and distinct from most other common words.

What to Learn Next

Prerequisites

思う (To think) 信じる (To believe) 本当 (Truth) 確実 (Certain) 理由 (Reason)

Learn Next

断言する (To assert) 見極める (To ascertain) 証明する (To prove) 納得する (To be satisfied/convinced) 決意する (To resolve)

Advanced

蓋然性 (Probability) 論理的帰結 (Logical consequence) 客観的妥当性 (Objective validity) 不可避 (Inevitable) 自明の理 (Self-evident truth)

Grammar to Know

~と確信する (Clause marking)

彼は明日雨が降ると確信している。

~を確信する (Object marking)

彼女は自分の勝利を確信した。

~ていく (Progressive state)

証拠が集まるにつれ、確信を深めていった。

~はずがない (Strong denial)

彼が失敗するはずがないと確信している。

~に違いない (Must be)

犯人は彼に違いないと確信している。

Examples by Level

私はこれが私の鍵だと確信しています。

I am sure these are my keys.

Uses the polite ~te imasu form for a current state.

彼は勝つと確信しています。

He is sure he will win.

~to marks the content of the certainty.

お母さんは僕が来ると確信していた。

Mom was sure I would come.

Past tense ~te ita shows a past state of mind.

明日、晴れると確信しています。

I am sure it will be sunny tomorrow.

Plain form verb + to + kakushin.

彼女はそれが本当だと確信した。

She became sure that it was true.

Kakushin shita marks the moment of becoming sure.

道が正しいと確信しています。

I am sure the road is correct.

Noun + da + to + kakushin.

この本は面白いと確信している。

I am sure this book is interesting.

I-adjective + to + kakushin.

犬が外にいると確信しています。

I am sure the dog is outside.

Verb indicating existence + to + kakushin.

テストに合格すると確信しています。

I am convinced I will pass the test.

Expresses high confidence in a future event.

彼は嘘をついていないと確信した。

I was convinced he wasn't lying.

Negative plain form + to + kakushin.

このチームが優勝すると確信しています。

I am sure this team will win the championship.

Topic + ga + verb + to + kakushin.

彼女ならできると確信しているよ。

I'm sure you can do it (to her).

The particle 'yo' adds a friendly, encouraging tone.

自分の選択が正しいと確信している。

I am convinced my choice is correct.

Noun + ga + adjective + to + kakushin.

彼はきっと来ると確信していた。

I was sure he would definitely come.

'Kitto' (definitely) reinforces the certainty.

これが一番いい方法だと確信しました。

I became convinced that this is the best way.

'Ichiban ii' (best) + noun + da + to.

成功を確信して、彼は努力を続けた。

Convinced of success, he continued his efforts.

~te form used to connect two actions/states.

市場の動向から、売上が伸びると確信しています。

Based on market trends, I am convinced sales will grow.

'Kara' indicates the basis for the conviction.

犯人は彼ではないと確信しています。

I am convinced he is not the culprit.

Formal negative 'dewa nai' + to.

努力は必ず報われると確信しています。

I am convinced that effort is always rewarded.

Abstract concept + to + kakushin.

彼の表情を見て、何かを隠していると確信した。

Seeing his expression, I was convinced he was hiding something.

~te form of 'miru' used as a reason.

このプロジェクトは社会に貢献すると確信しています。

I am convinced this project will contribute to society.

Professional context usage.

自分たちの勝利を確信している選手たちは、落ち着いていた。

The players, convinced of their victory, were calm.

Relative clause modifying 'senshu-tachi'.

彼が約束を破るはずがないと確信している。

I am convinced there is no way he would break his promise.

'Hazu ga nai' (no way) + to + kakushin.

新しい技術の可能性を確信しました。

I became convinced of the potential of the new technology.

Noun + no + noun + wo + kakushin.

綿密な調査の結果、我々は彼の無実を確信した。

As a result of a thorough investigation, we were convinced of his innocence.

'No kekka' (as a result) provides the logical basis.

この政策が経済を立て直すと確信しております。

I am convinced that this policy will revitalize the economy.

Humble 'orimasu' used for formal speeches.

彼女の才能がいつか開花することを確信して疑わなかった。

I never doubted and was convinced that her talent would bloom someday.

'Shinjite utagawanai' nuance added via context.

データに基づき、この傾向は続くと確信できます。

Based on the data, we can be convinced that this trend will continue.

Potential form 'kakushin dekiru'.

彼の一言で、私はすべてが仕組まれていたのだと確信した。

With his single word, I was convinced that everything had been set up.

'No da' (explanatory) + to + kakushin.

お客様に満足していただけると確信しております。

I am convinced that our customers will be satisfied.

Humble/Polite 'itadakeru' + to + kakushin.

歴史が我々の正しさを証明すると確信している。

I am convinced that history will prove us right.

Philosophical/Political context.

その場の空気から、交渉の失敗を確信せざるを得なかった。

From the atmosphere of the place, I had no choice but to be convinced of the negotiation's failure.

'Sezaru wo enakatta' (had no choice but to).

独自の理論を構築する中で、彼は宇宙の真理を確信した。

In the process of constructing his own theory, he became convinced of the truth of the universe.

Complex 'naka de' (in the process of) structure.

国民の支持が得られると確信し、彼は出馬を決意した。

Convinced that he could gain the support of the people, he decided to run for office.

Clause + kakushin shi (conjunctive form) + main clause.

証拠は状況的なものに過ぎなかったが、刑事は直感的に彼の有罪を確信していた。

The evidence was merely circumstantial, but the detective intuitively was convinced of his guilt.

'Ni sugina katta' (was merely) contrast.

この革新的な手法が、業界の常識を覆すと確信しています。

I am convinced that this innovative method will overturn the industry's common sense.

High-level business vocabulary (kutsugaesu).

教育こそが貧困を撲滅する鍵であると確信してやまない。

I cannot help but be convinced that education is the key to eradicating poverty.

'~te yamanai' (do not stop / strongly feel).

長年の研究により、この物質の有用性を確信するに至った。

Through years of research, I have come to be convinced of this substance's utility.

'Ni itatta' (reached the point of).

対話の重要性を確信しているからこそ、我々は交渉を続ける。

It is precisely because we are convinced of the importance of dialogue that we continue negotiations.

'Kara koso' (precisely because) for emphasis.

自身の信念に基づき、彼はそれが唯一の道であると確信した。

Based on his own beliefs, he was convinced that it was the only path.

'Ni motozuki' (based on).

科学的実証主義の限界を認めつつも、彼は客観的真理の存在を確信していた。

While acknowledging the limits of scientific positivism, he was convinced of the existence of objective truth.

'~tsutsu mo' (while/despite) structure.

言葉の壁を超えた共感の可能性を確信することは、現代社会における希望である。

Being convinced of the possibility of empathy that transcends language barriers is a hope in modern society.

Nominalized clause + koto wa + predicate.

不確実性が支配する世界において、確信を持つことは一種の勇気である。

In a world dominated by uncertainty, having conviction is a form of courage.

Abstract philosophical sentence.

彼は、芸術が魂を救済する唯一の手段であると確信して疑わなかった。

He never doubted and was convinced that art was the only means of saving the soul.

Literary 'shinjite utagawanai' equivalent.

歴史の必然性を確信する彼の言説は、多くの若者を熱狂させた。

His discourse, which expressed conviction in the inevitability of history, enthralled many young people.

Modified noun 'gensetsu' (discourse).

いかなる困難が待ち受けていようとも、勝利を確信する心は揺るがない。

No matter what difficulties lie ahead, a heart convinced of victory will not waver.

'Ikanaru... tomo' (no matter what).

自己の存在の根源を確信するためには、深い内省が必要である。

To be convinced of the root of one's existence, deep introspection is necessary.

'Tame ni wa' (in order to).

万物が流転する中で、普遍的な価値を確信することは至難の業だ。

In a world where all things are in flux, being convinced of universal values is an extremely difficult task.

'Jin-nan no waza' (extremely difficult task).

Common Collocations

勝利を確信する

成功を確信する

無実を確信する

手応えを確信する

将来を確信する

直感を確信する

真実を確信する

愛を確信する

敗北を確信する

必要性を確信する

Common Phrases

確信に満ちた

— Full of conviction. Used to describe a look or tone.

彼は確信に満ちた声で話した。

確信を得る

— To gain certainty. Used when evidence clears doubt.

調査の結果、確信を得た。

確信を深める

— To deepen one's conviction. Used when more proof arrives.

その一言で確信を深めた。

確信犯

— Originally: Someone who acts on moral conviction. Now often: Doing something wrong knowing it's wrong.

彼は確信犯としてその行動を取った。

確信がない

— To have no certainty. Used when unsure.

まだ成功する確信がない。

確信を持つに至る

— To reach the point of having conviction.

多くの実験を経て、確信を持つに至った。

確信を揺るがす

— To shake someone's conviction.

新たな証拠が彼の確信を揺るがした。

確信を持って言える

— Can say with conviction. Used for strong claims.

これだけは確信を持って言える。

確信に近づく

— To get closer to certainty.

真実の確信に近づいている。

確信しきっている

— To be completely and utterly convinced.

彼は自分が勝つと確信しきっている。

Often Confused With

確信する vs 信じる

Shinjiru is about faith; Kakushin is about reasoned certainty.

確信する vs 確実

Kakujitsu is an adjective (certain); Kakushin is a verb/noun (conviction).

確信する vs 確認

Kakunin is to check/confirm; Kakushin is to be already convinced.

Idioms & Expressions

"目から鱗が落ちる"

— To have the scales fall from one's eyes; a sudden epiphany leading to conviction.

彼の説明を聞いて目から鱗が落ち、成功を確信した。

Literary/Common

"太鼓判を押す"

— To give a guarantee or a seal of approval based on conviction.

彼なら合格すると、先生が太鼓判を押した。

Idiomatic

"胸を張る"

— To puff out one's chest with pride and conviction.

彼は勝利を確信し、胸を張って歩いた。

Common

"腹を据える"

— To settle one's belly; to make a firm decision with conviction.

彼は成功を確信し、腹を据えて取り組んだ。

Idiomatic

"肝に銘じる"

— To engrave in one's heart; to be deeply convinced of a lesson.

忠告を肝に銘じ、次回の成功を確信した。

Formal

"手に取るようにわかる"

— To understand as if picking it up; to be clearly convinced of a situation.

彼の嘘が手に取るようにわかり、犯人だと確信した。

Common

"疑いの余地がない"

— No room for doubt; the state of absolute conviction.

彼の有罪は疑いの余地がなく、誰もが確信した。

Formal

"一寸先は闇"

— One inch ahead is darkness; used as a contrast to 'kakushin.'

一寸先は闇だが、私は成功を確信している。

Proverb

"石橋を叩いて渡る"

— To tap a stone bridge before crossing; being cautious before 'kakushin.'

石橋を叩いて渡る性格だが、今回は確信がある。

Proverb

"待てば海路の日和あり"

— Wait and there will be good weather for sailing; having conviction in patience.

成功を確信し、待てば海路の日和ありと信じている。

Proverb

Easily Confused

確信する vs 革新 (Kakushin)

Identical pronunciation.

Innovation vs. Conviction. Kanji are different (革新 vs 確信).

技術革新 (Technological innovation).

確信する vs 確信犯 (Kakushin-han)

Used colloquially to mean 'knowing it's bad.'

Originally meant acting on moral conviction; now often misused for intentional mischief.

彼は確信犯で遅刻した。

確信する vs 核心 (Kakushin)

Identical pronunciation.

The core or heart of a matter vs. conviction.

問題の核心に迫る。

確信する vs 確証 (Kakushou)

Similar meaning.

Physical or logical proof vs. the internal state of certainty.

確証がない。

確信する vs 断定 (Dantei)

Similar meaning.

Making a definitive conclusion/statement vs. the internal feeling of certainty.

まだ断定はできない。

Sentence Patterns

[Noun] + だと確信しています。

これは僕のペンだと確信しています。

[Verb Plain] + と確信しています。

彼は来ると確信しています。

[Noun] + を確信している。

勝利を確信している。

[Negative Clause] + と確信している。

彼は犯人ではないと確信している。

[Basis] + から、[Clause] + と確信している。

データから、成功すると確信している。

[Noun] + に確信を持つに至る。

真実を確信するに至った。

[Clause] + と確信して疑わない。

平和が来ると確信して疑わない。

[Abstract Noun] + の [Noun] + を確信する。

歴史の必然性を確信する。

Word Family

Nouns

確信 (Certainty/Conviction)

確信犯 (Moral offender/Intentional act)

Verbs

確信する (To be convinced)

Adjectives

確信に満ちた (Full of conviction)

確認 (Confirmation)

正確 (Accurate)

信用 (Trust)

信頼 (Reliance)

信念 (Belief)

How to Use It

frequency

Common in media, business, and formal speech. Moderate in casual daily life.

Common Mistakes

Using 'ni' for the object. → Using 'wo' or 'to'.
'Kakushin' is a transitive verb. You 'kakushin' a thing (wo) or a thought (to).
Using it for weak guesses. → Using 'omou' or 'kamoshirenai'.
'Kakushin' is 100% certainty. Using it for a 50/50 guess sounds weird.
Confusing with 'kakunin'. → Using 'kakunin' for checking.
'Kakunin' is a physical action of checking. 'Kakushin' is a mental state.
Forgetting 'suru'. → 'Kakushin suru'.
'Kakushin' alone is a noun. You need 'suru' to make it a verb.
Using plain form for current state. → 'Kakushin shite iru'.
Plain 'kakushin suru' sounds like you are deciding to be sure right now.

Tips

Use with Evidence

Use 'kakushin suru' when you have a reason or evidence to be sure. It makes your statement much more persuasive.

Te-iru is Key

Most of the time, you should use 'kakushin shite iru' because conviction is a state that lasts over time, not a momentary action.

Business Confidence

In business, using 'kakushin' shows you are a reliable partner who believes in their work.

Kanji Meaning

Remember 確 (solid) + 信 (belief). If your belief is 'solid' like a rock, it is 'kakushin.'

Vs. Shinjiru

If you trust a person's heart, use 'shinjiru.' If you are sure of a factual outcome, use 'kakushin suru.'

Anime Tropes

Listen for heroes saying 'shouri wo kakushin shita' right before their final attack.

Essay Conclusions

'以上の理由から、私は...と確信する' is a classic way to end a strong Japanese essay.

Encouragement

Telling a friend 'Kimi no seikou wo kakushin shite iru' is a very high form of praise.

Avoid Overuse

Don't use it for every small thought, or you will sound like you are constantly making dramatic proclamations.

The Core of the Matter

Don't confuse it with '核心' (core), which sounds the same. Context is everything!

Memorize It

Mnemonic

Think of 'Kaku' as 'Concrete' (it sounds a bit like the start of 'Kakujitsu' - certain) and 'Shin' as 'Sincere' belief. When your belief is as solid as concrete, you 'Kakushin.'

Visual Association

Imagine a person standing on a massive, solid rock (Kaku) while holding a scroll of truth (Shin). They are unshakeable.

Word Web

確実 (Certain) 信念 (Belief) 確認 (Confirm) 信用 (Trust) 証拠 (Evidence) 論理 (Logic) 直感 (Intuition) 自信 (Confidence)

Challenge

Try to use 'kakushin shite iru' today instead of 'omou' when you are talking about something you are 100% sure about.

Word Origin

The word is a Sino-Japanese compound (Kango). 'Kaku' (確) originates from the concept of a stone being solid and unmoving. 'Shin' (信) originates from a person (人) standing by their words (言), representing trust and truth.

Original meaning: To firmly trust or to have a solid belief.

Sino-Japanese (Kango)

Cultural Context

Be careful using 'kakushin' in sensitive negotiations; it can sound like you are unwilling to compromise.

In English, we often say 'I'm positive' or 'I'm 100% sure.' These are the closest equivalents to 'kakushin shite iru.'

Detective Conan often uses 'kakushin' when solving a case. Political speeches by Japanese Prime Ministers frequently use 'kakushin' to show resolve.

Practice in Real Life

Real-World Contexts

Business Meeting

成功を確信しています。
データに基づき確信を得ました。
確信を持って提案します。
将来性を確信しております。

Sports Interview

勝利を確信した瞬間でした。
自分の力を確信しています。
優勝を確信して疑いません。
練習の成果を確信しています。

Mystery Novel/Drama

犯人は彼だと確信した。
証拠を見て確信を深めた。
彼の嘘を確信している。
有罪を確信させる証拠。

Personal Advice

君ならできると確信している。
正しい道だと確信して進め。
自分の直感を確信しなさい。
努力が報われると確信している。

Academic Research

仮説の正しさを確信した。
理論の有用性を確信している。
確信に至るまでのプロセス。
実験結果から確信を得た。

Conversation Starters

"どうしてそんなに成功すると確信しているのですか？ (Why are you so convinced of success?)"

"あなたが人生で一番確信した瞬間はいつですか？ (When was the moment in your life you were most convinced?)"

"証拠がなくても、何かを確信することはありますか？ (Do you ever feel convinced of something even without evidence?)"

"新しい技術が世界を変えると確信していますか？ (Are you convinced that new technology will change the world?)"

"自分の直感を信じて確信することは得意ですか？ (Are you good at trusting your intuition and being convinced?)"

Journal Prompts

今日、自分が正しいと確信した出来事について書いてください。 (Write about something today you were convinced was right.)

将来の夢が叶うと確信していますか？その理由は何ですか？ (Are you convinced your future dreams will come true? Why?)

誰かに「君ならできる」と確信を持って言われたことはありますか？ (Have you ever been told 'you can do it' with conviction?)

確信を持って行動することの重要性について考えてみましょう。 (Think about the importance of acting with conviction.)

もし確信が持てない時、あなたはどうやって決断しますか？ (If you can't feel convinced, how do you make a decision?)

Frequently Asked Questions

10 questions

Generally no. It sounds too heavy for things like 'I'm sure I left my phone at home.' Use 'zettai' or 'omou' instead.

'Kakunin' is the act of checking (e.g., checking a flight time). 'Kakushin' is the result of being sure (e.g., being convinced the trip will be fun).

Yes, but usually as an observation: 'Kare wa seikou wo kakushin shite iru you da' (He seems convinced of success).

Yes, it is one of the strongest ways to express certainty in Japanese.

Rarely. It's usually for positive assertions or legal/logical conclusions.

'Kakushin ga nai' or 'Kakushin dekinai.'

Yes, both use 確 (certain).

In modern slang, yes. In strict legal or philosophical terms, no.

'Shinnen' or 'shinkou' are more common for religion, but 'kakushin' can be used for the certainty of a specific religious truth.

'Kakushin shite orimasu.'