Explanation at your level:
Hello! 〜ことにする (koto ni suru) is a phrase that helps you say you have made a choice. Imagine you want ice cream. You can say, 'I decided to eat ice cream!' In Japanese, you can say アイスクリームを食べことにする (aisukurīmu o taberu koto ni suru). It's like telling someone what you have decided to do. You use it after you think about something and pick one thing to do. It's a very common way to talk about your plans!
The expression 〜ことにする (koto ni suru) is used when you make a decision about an action. You attach it to the basic form of a verb. For example, if you decide to go home, you say 家に帰ることにする (ie ni kaeru koto ni suru). If you decide not to buy something, you use the negative form: 買わないことにする (kawanai koto ni suru). This phrase is very useful for explaining your personal choices in everyday situations, like deciding what to eat or where to go.
〜ことにする (koto ni suru) is a versatile expression used to indicate that you have made a personal decision to do something. It's formed by taking the plain form of a verb and adding 〜ことにする. For instance, 旅行することにした (ryokō suru koto ni shita) means 'I decided to travel.' It implies a conscious choice has been made. You can use it in various contexts, from simple daily choices like 今日は早く寝ることにします (Kyō wa hayaku neru koto ni shimasu) - 'I'll decide to sleep early today' - to more significant decisions.
The grammatical construction 〜ことにする (koto ni suru) signifies the act of making a personal resolution or decision. It's typically appended to the plain form of a verb. The nuance here is that it emphasizes the speaker's agency in the decision-making process. For example, この件は保留することにしました (Kono ken wa horyū suru koto ni shimashita) translates to 'I've decided to put this matter on hold,' indicating a deliberate choice. It's distinct from decisions made by external factors or group consensus, focusing solely on the individual's resolve.
〜ことにする (koto ni suru) functions as a verbal phrase indicating a personal resolution or decision. It is conjugated with the plain form of a verb (dictionary, nai, or ta-form) and signifies that the speaker has opted for a particular course of action after consideration. For example, 将来は海外で働くことにする (Shōrai wa kaigai de hataraku koto ni suru) - 'In the future, I've decided to work abroad' - illustrates a significant life choice. The expression underscores the subjective nature of the decision, differentiating it from objective statements or externally imposed choices. It can also be used retrospectively, as in あのレストランに行くことにした (Ano resutoran ni iku koto ni shita) - 'I decided to go to that restaurant.'
The construction 〜ことにする (koto ni suru) is a fundamental Japanese expression for articulating a personal decision or commitment. Grammatically, it nominalizes a preceding verb phrase using こと (koto), which is then followed by the verb する (suru), effectively meaning 'to make [the action] a matter of doing'. This structure emphasizes the speaker's volition and the finality of the choice, often implying a process of deliberation. For instance, 長年の懸案事項だったプロジェクトを中止することに決定した (Naganen no ken'an jikō datta purojekuto o chūshi suru koto ni kettei shita) - 'The project, which had been a pending issue for many years, was decided to be cancelled' - showcases its use in formal contexts, although the core meaning remains personal resolution. The nuance lies in its contrast with passive decisions or external mandates, highlighting the speaker's active role in shaping their actions.
Word in 30 Seconds
- 〜ことにする means 'to decide to do'.
- It's attached to the plain form of a verb.
- Emphasizes personal volition and commitment.
- Used for present/future decisions (〜ことにします) and past decisions (〜ことにしました).
Hey there! Let's dive into the super useful Japanese expression 〜ことにする (koto ni suru). You'll hear this all the time, and it's a fantastic way to express that you've made a decision. Think of it as your personal declaration: 'I've decided to do X!' or 'I'll go with Y!'
It's all about making a choice and committing to it. Whether you're deciding what to eat for dinner, which route to take, or even a bigger life choice, 〜ことにする is your go-to phrase. It highlights that the decision is *yours* and you're moving forward with it. It’s a really common and natural way to talk about your intentions and plans.
The structure 〜ことにする is a combination of a nominalizer (こと - koto, meaning 'thing' or 'matter') and the verb する (suru, meaning 'to do'). So, literally, it's like 'to do the matter of...' or 'to make it a thing of doing...'. This grammatical pattern has evolved over time in Japanese to become a standard way to express decision-making.
While it's hard to pinpoint an exact historical 'invention' date, this kind of construction, using こと to turn a verb phrase into a noun-like concept that can then be acted upon by する, is fundamental to Japanese grammar. It allows for abstract ideas and actions to be treated as concrete 'things' that can be decided upon or performed. It's a testament to how flexible Japanese grammar is in expressing nuanced meanings through combinations of particles and verbs.
You'll use 〜ことにする whenever you want to state that you've made a decision. It's typically attached to the plain form of a verb. For example, if you decide to eat, you'd say 食べことにする (taberu koto ni suru). If you decide to go, it's 行くことにする (iku koto ni suru).
It's important to note that this expression usually implies a personal decision, often one that might have involved some thought or consideration. It's less common for stating universally agreed-upon facts or decisions made by a group unless you're specifically stating your agreement. You might hear variations like 〜ことにしました (koto ni shimashita) in the past tense, meaning 'I decided to...' This is super common in everyday conversation.
Common Collocations:
- 決める (kimeru): While 〜ことにする already means 'to decide', you might sometimes hear 〜ことに決める (koto ni kimeru), which emphasizes the act of 'deciding upon' something.
- これから (korekara): Often used with future decisions, like 'From now on, I've decided to...'.
While 〜ことにする itself isn't an idiom, it's a core part of many decision-making expressions. Here are some related ideas:
- 腹を据える (hara o sueru): This means to make up one's mind firmly, to be resolved. It's a stronger, more determined decision than just deciding what to eat. Example: 彼は危険な任務に腹を据えた。(Kare wa kiken na ninmu ni hara o sueta.) - He resolved himself to the dangerous mission.
- 意を決する (i o kessuru): Similar to 腹を据える, this means to make up one's mind resolutely, to take the plunge. Example: 彼女は意を決して、一人旅に出た。(Kanojo wa i o kesshite, hitoritabi ni deta.) - She made up her mind resolutely and went on a solo trip.
- 決断を下す (ketsudan o kudasu): This is a more formal way to say 'to make a decision' or 'to pass judgment'. Example: 会長は最終的な決断を下した。(Kaichō wa saishūteki na ketsudan o kudashita.) - The chairman made the final decision.
- まな板に載せる (manaita ni noseru): Literally 'to put on the cutting board', this idiom means to consider something seriously or to put something up for decision/discussion. Example: その問題は、会議でまな板に載せられた。(Sono mondai wa, kaigi de manaita ni noserareta.) - That issue was put on the table for discussion at the meeting.
- 腹が決まる (hara ga kimaru): This means one's mind is made up, one is resolved. It's the state of having decided firmly. Example: ついに腹が決まった。(Tsuini hara ga kimatta.) - Finally, my mind was made up.
Grammar: 〜ことにする is attached to the plain form of verbs (dictionary form, nai-form, ta-form). It functions as a way to express a decision.
- Verb (plain form) + ことにする
Examples:
- 行くことにする (iku koto ni suru) - decide to go
- 食べないことにする (tabenai koto ni suru) - decide not to eat
- 行ったことにする (itta koto ni suru) - decide to have gone (e.g., pretend)
Pronunciation:
- IPA (Japanese): /ko̞to̞ ni ̞sɯ̥ᵝɾɯ̟ᵝ/
- Breakdown: ko-to ni su-ru
- Sounds like: "koh-toh nee soo-roo"
- Stress: Generally, Japanese is flatter than English, but there's a slight emphasis on each mora (syllable-like unit).
- Common Errors: Sometimes learners might struggle with the 'tsu' sound in 'suru', making it too strong or too weak. Ensure the 'u' sound is not heavily rounded.
- Rhymes: While direct rhyming isn't a major feature of Japanese pronunciation in the same way as English, words with similar vowel endings can sound somewhat related. For example, words ending in '-u' like 'matsu' (待つ) or 'taberu' (食べる) share the final vowel sound.
Fun Fact
The use of 'koto' (こと) as a nominalizer is a key feature of Japanese grammar, allowing abstract concepts and actions to be treated as concrete nouns.
Pronunciation Guide
Sounds like 'koh-toh nee soo-roo', with a relatively flat intonation common in Japanese.
Similar to UK pronunciation, focusing on clear articulation of each syllable.
Common Errors
- Over-emphasizing the 'u' sound in 'suru'.
- Pronouncing the 'tsu' sound too strongly.
- Adding English-like stress patterns.
Rhymes With
Difficulty Rating
Requires understanding of verb conjugations and nominalizers.
Correct application of verb forms and context is key.
Natural usage depends on context and nuance.
Recognizing the phrase in conversation.
What to Learn Next
Prerequisites
Learn Next
Advanced
Grammar to Know
Verb Plain Forms
行く (iku), 食べる (taberu), する (suru)
Nominalizers (こと, の)
The use of こと to turn verbs into noun phrases.
Expressing Intentions and Plans
Comparing 〜ことにする, 〜つもりだ, 〜ようにする.
Examples by Level
わたしはジュースを飲むことにします。
I / juice / drink / decide to do.
Use the dictionary form of the verb + ことにする.
あした、公園に行くことにします。
Tomorrow / park / go / decide to do.
〜ことにします is the polite present/future form.
この本を読むことにします。
This / book / read / decide to do.
The decision is personal.
えいがを見ることにします。
Movie / watch / decide to do.
Use 〜ことにします for your own choices.
今日は、早く寝ることにします。
Today / early / sleep / decide to do.
〜こと にします expresses a resolution.
かれは、新しいくつを買うことにします。
He / new / shoes / buy / decides to do.
Can be used for third person decisions too, but often implies the speaker knows or agrees.
わたしは、コーヒーを飲むことにしました。
I / coffee / drink / decided to do.
〜ことにしました is the past tense.
どこへ行くことにしますか？
Where / go / decide to do / ?.
This is asking about someone else's decision.
明日は、図書館で勉強することにしました。
Tomorrow / library / study / decided to do.
Past tense 〜ことにしました indicates a decision already made.
このレストランで食事をすることにしましょう。
This / restaurant / meal / eat / let's decide to do.
〜ことにしましょう is a suggestion to make a decision together.
彼は、転職しないことに決めたようです。
He / job change / not do / decided / seems.
〜ないことにする is used for deciding *not* to do something.
彼女は、もっと運動することにしました。
She / more / exercise / decided to do.
The plain form of the verb is used before ことにする.
私たちは、来週、会議を開くことにしました。
We / next week / meeting / hold / decided to do.
Can be used for group decisions when stating the outcome.
この問題については、後で考えることにしましょう。
This / problem / about / later / think / let's decide to do.
〜ことにしましょう is a polite suggestion for a joint decision.
彼は、その提案を受け入れることにした。
He / that / proposal / accept / decided to do.
Plain past tense 〜ことにした is common in narrative.
あなたは、どのコースを選ぶことにしますか？
You / which / course / choose / decide to do / ?.
Asking someone about their decision using 〜ことにしますか？
健康のために、毎日ジョギングすることにしました。
For health / every day / jogging / decided to do.
Indicates a resolution for personal benefit.
この件については、上司に相談することにします。
This matter / about / boss / consult / will decide to do.
Shows a planned course of action after consideration.
新しい趣味を見つけるために、週末は新しいことに挑戦することにしました。
New / hobby / find / in order to / weekend / new things / try / decided to do.
Expresses a proactive decision to explore new interests.
彼は、長年勤めた会社を辞めることに決めた。
He / many years / worked for / company / quit / decided to do.
Past tense 〜ことに決めた implies a firm decision has been made.
このプロジェクトは、一旦中止することにしましょう。
This / project / for now / halt / let's decide to do.
〜ことにしましょう suggests a collective decision or proposal.
将来のために、貯金を増やすことにしました。
Future / for the sake of / savings / increase / decided to do.
Highlights a decision made with future goals in mind.
彼女は、その誘いを断ることにした。
She / that / invitation / refuse / decided to do.
Used when deciding against an option.
私たちは、もっと環境に優しい生活を送ることにしようと話し合っています。
We / more / environmentally friendly / life / live / let's decide to do / are discussing.
〜ことにしよう indicates a decision being considered or proposed within a group.
長年の夢だった海外移住を、ついに実行することにしました。
Many years / dream / was / overseas emigration / finally / execute / decided to do.
Implies a significant personal decision after long contemplation.
この複雑な状況を鑑み、我々は慎重に進むことにします。
This / complex situation / considering / we / cautiously / proceed / will decide to do.
Formal usage, often in business or official contexts, emphasizing a chosen strategy.
彼は、自身のキャリアパスについて再考し、独立することに決めた。
He / his own / career path / about / reconsider / start own business / decided to do.
Indicates a decisive shift in personal direction.
会議の結果、この提案を却下することに決定いたしました。
Meeting / result / this / proposal / reject / decided to do / decided (formal).
Formal past tense, often used in official announcements or reports.
環境保護のため、使い捨てプラスチックの使用を段階的に廃止することにしました。
Environmental protection / for the sake of / disposable plastic / usage / gradually / abolish / decided to do.
Demonstrates a policy decision with a clear objective.
その芸術家は、伝統的な技法にとらわれず、独自の表現を追求することに情熱を注いでいる。
That / artist / traditional / techniques / bound by / not / unique / expression / pursue / passionate about.
Describes an ongoing commitment to a chosen artistic direction.
家族会議の結果、来年から海外赴任を受け入れることにしました。
Family meeting / result / from next year / overseas assignment / accept / decided to do.
Implies a decision reached after group discussion and consensus.
この問題の解決策として、より抜本的なアプローチを取ることにしましょう。
This / problem / solution / as / more / fundamental / approach / take / let's decide to do.
A proposal for a significant change in strategy.
長年の研究を経て、彼はその難病の治療法を確立することに成功した。
Many years / research / after going through / he / that / difficult disease / treatment method / establish / succeeded in doing.
Implies a culmination of effort leading to a significant decision/achievement.
社会的な責任を鑑み、企業は持続可能な開発目標を達成することにコミットする。
Societal / responsibility / considering / company / sustainable / development goals / achieve / commit to do.
Formal statement of corporate commitment or policy.
彼は、既存の枠組みにとらわれず、全く新しいビジネスモデルを創出することに人生を捧げた。
He / existing / framework / bound by / not / completely new / business model / create / dedicated his life to doing.
Expresses a profound life choice and dedication.
その政治家は、国民の負託に応えるべく、改革断行を決意した。
That / politician / citizens' trust / respond to / in order to / reform / carry out decisively / decided to do.
Formal declaration of intent to enact significant changes.
我々は、この危機的状況を乗り越えるため、前例のない協力体制を構築することに合意した。
We / this / crisis situation / overcome / in order to / unprecedented / cooperative structure / build / agreed to do.
Indicates a formal agreement on a significant course of action.
彼女は、自己実現のために安定した職を辞し、芸術の道に進むことを選んだ。
She / self-realization / for the sake of / stable job / quit / art / path / proceed / chose to do.
Highlights a personal choice prioritizing self-fulfillment over security.
この問題の根源に対処するため、我々はより根本的な解決策を実施することにいたしました。
This / problem / root cause / address / in order to / we / more / fundamental / solution / implement / decided to do (polite).
Formal phrasing indicating a decision to tackle underlying issues.
文化交流を促進するため、両国は相互理解を深める新たなプログラムを開始することに合意した。
Cultural exchange / promote / for the sake of / both countries / mutual understanding / deepen / new program / start / agreed to do.
Formal agreement on initiating a new collaborative venture.
長年の熟慮の末、彼は世俗的な成功よりも精神的な充足を追求することに人生の舵を切ることを決意した。
Many years / deep consideration / end / he / worldly / success / rather than / spiritual / fulfillment / pursue / decided to steer his life.
Emphasizes a profound, life-altering decision based on deep introspection.
人類共通の課題である気候変動に対し、国際社会は抜本的な対策を講じることに合意し、その履行を誓約した。
Humanity's common / challenge / climate change / towards / international community / fundamental / measures / take / agreed to do / its / implementation / pledged.
Formal declaration of international commitment to address a critical global issue.
彼は、既成概念の打破と創造性の解放を目指し、既存の芸術界の枠組みを超越することに生涯を捧げる覚悟を決めた。
He / established ideas / breaking / creativity / liberation / aiming for / existing / art world / framework / transcend / decided to dedicate his life to doing.
Signifies a lifelong dedication to challenging norms and fostering innovation.
その哲学者によれば、真の自由とは、外部の制約から解放され、自己の理性に従って生きることを選択することにある。
That / philosopher / according to / true / freedom / external / constraints / liberation / oneself / reason / follow / live / choose to do / lies in.
Philosophical statement on freedom as a conscious choice based on reason.
我々は、この未曾有の危機を克服するために、国家間の利害を超えた、かつてない規模での協調体制を確立することに合意した。
We / this / unprecedented / crisis / overcome / in order to / between nations / interests / beyond / never before seen / scale / cooperative structure / establish / agreed to do.
Formal agreement on establishing a large-scale cooperative framework transcending national interests.
彼女は、物質的な豊かさよりも、精神的な探求と自己成長に重きを置く生き方を選択し、その決意を固めた。
She / material / abundance / rather than / spiritual / pursuit / self-growth / emphasis / place / way of life / chose / that / determination / solidified.
A deeply personal choice prioritizing intangible values over material possessions.
この根深い社会問題の解決には、表層的な対症療法ではなく、構造的な変革を断行することこそが不可欠であるとの結論に至った。
This / deep-rooted / social problem / solution / superficial / symptomatic treatment / rather than / structural / reform / carry out decisively / is essential / reached the conclusion.
Conclusion reached after analysis, advocating for fundamental structural change.
両国政府は、文化遺産の保護と継承を目的とした、かつてないレベルでの学術的・芸術的交流を推進することに合意し、そのための包括的な枠組みを構築することで一致した。
Both countries' governments / cultural heritage / protection / inheritance / purpose / unprecedented / level / academic / artistic exchange / promote / agreed to do / for that purpose / comprehensive framework / build / agreed.
Formal agreement on establishing a comprehensive framework for unprecedented cultural and academic exchange.
Common Collocations
Idioms & Expressions
"腹を据える (hara o sueru)"
To make up one's mind firmly; to be resolved.
彼はどんな困難にも立ち向かうよう腹を据えた。
neutral"意を決する (i o kessuru)"
To make up one's mind resolutely; to take the plunge.
彼女は意を決して、新しい事業を始めた。
formal"決断を下す (ketsudan o kudasu)"
To make a decision; to pass judgment (formal).
リーダーは最終的な決断を下さなければならない。
formal"まな板に載せる (manaita ni noseru)"
To put something on the table for discussion or decision.
その提案は、会議でまな板に載せられた。
neutral"腹が決まる (hara ga kimaru)"
One's mind is made up; to be resolved.
ついに、彼は転職する腹が決まったようだ。
neutral"清水の舞台から飛び降りる (Kiyomizu no butai kara tobioriru)"
To take a leap of faith; to make a risky decision.
借金をしてまで事業を始めるのは、清水の舞台から飛び降りるようなものだ。
idiomaticEasily Confused
Both involve 'suru' and express future actions or intentions.
〜ことにする is a firm decision ('I have decided to...'). 〜ようにする is about making an effort or trying ('I will try to...').
毎日運動することにしました。(I decided to exercise every day.) vs. 毎日運動するようにしています。(I am trying to exercise every day.)
Both relate to deciding.
決める is a general verb for deciding. 〜ことにする is a specific grammatical construction emphasizing personal volition and commitment.
予定を決めました。(I decided the plans - could be anyone's decision.) vs. 旅行することにしました。(I decided to travel - emphasizes my personal choice.)
Both relate to actions one should take.
〜べきだ expresses obligation or strong recommendation ('should do'). 〜ことにする expresses a personal decision ('I have decided to do').
もっと勉強すべきだ。(You should study more - obligation.) vs. もっと勉強することにしました。(I decided to study more - personal choice.)
Both express intention or future plans.
〜つもりだ means 'intend to do' or 'plan to do'. 〜ことにする means 'have decided to do'. 〜ことにする implies a more finalized decision.
明日、映画を見るつもりです。(I intend to watch a movie tomorrow.) vs. 明日、映画を見ることにしました。(I decided to watch a movie tomorrow.)
Sentence Patterns
Verb (plain form) + ことにする
明日、早く起きることにします。
Negative Verb (nai form) + ことにする
甘いものを食べないことにします。
Verb (ta form) + ことにする
彼はその提案を受け入れることにした。
Subject + は/が + Verb (plain form) + ことにする
私は、この本を読むことにします。
Verb (plain form) + ことにしましょう
みんなで協力することにしましょう。
Word Family
Nouns
Verbs
Related
How to Use It
Formality Scale
Common Mistakes
〜ことにする emphasizes personal volition. Saying 'The train will depart at 10' as '電車は10時に出発することにする' is incorrect.
Saying '食べますことにする' (tabemasu koto ni suru) instead of '食べることにする' (taberu koto ni suru) is grammatically incorrect.
Saying '毎日運動することにしました' (I decided to exercise every day) is different from '毎日運動するようにしています' (I am trying to exercise every day).
While 〜ことにする can be used formally, its core meaning is personal decision, which might be too informal in certain contexts.
Saying '昨日、行くことにします' (Kinō, iku koto ni shimasu) is incorrect; it should be '昨日、行くことにしました' (Kinō, iku koto ni shimashita).
Tips
Connect 'Koto' to 'Quote'
Remember 'koto' as a 'quote' of your decision. You're quoting what you've decided to do. Then 'suru' means you're sure you'll do it!
Own Your Decisions
Native speakers use 〜ことにする to emphasize that the decision is *theirs*. Use it when you want to highlight your personal choice.
Personal vs. Group
While 〜ことにする is personal, 〜ことにしましょう is a great way to suggest a group decision politely. It balances personal choice with group harmony.
Plain Form Power
Always remember to use the plain form (dictionary, nai, ta) of the verb before 〜ことにする. Avoid polite forms like 〜ます.
Smooth 'Suru'
Practice the 'su-ru' sound. Don't make the 'u' too rounded or the 'tsu' too sharp. Aim for a clear, natural flow.
Avoid External Decisions
Don't use 〜ことにする for things decided by others (like train schedules). Stick to 決める or 決定する for those.
Nominalizer Magic
The 'koto' (こと) here is a powerful grammar tool called a nominalizer. It turns verbs into noun-like phrases, making grammar flexible!
Decision Diary
Keep a small 'decision diary' for a week. Write down 3 things each day you decided to do using 〜ことにします or 〜ことにしました.
Past Tense is Key
For recounting past decisions, always use 〜ことにしました. It's one of the most common ways to talk about what you decided yesterday or last week.
Negative Decisions
Remember to use the 'nai' form of the verb for negative decisions: 〜ないことにする (decide not to do).
Memorize It
Mnemonic
Think of 'koto' as 'quote' (what you decided) and 'suru' as 'sure' (you are sure about it). 'Quote, I'm sure I'll do it!'
Visual Association
Imagine someone writing down their decision in a notebook ('koto' like a note) and then confidently nodding ('suru' like a nod of agreement).
Word Web
Challenge
Try making 5 decisions you'll make today using 〜ことにします.
Word Origin
Japanese
Original meaning: To make the matter/thing of doing.
Cultural Context
Generally neutral, but the emphasis on personal decision can sometimes contrast with cultural norms that value group harmony or deference to authority.
In English, we might say 'I've decided to...', 'I'll go with...', 'I've made up my mind to...'. The Japanese phrase is very direct about personal choice.
Practice in Real Life
Real-World Contexts
Making daily choices
- 今日のランチはパスタにすることにしました。
- 今日は早く寝ることにします。
- この本を読むことにします。
Discussing future plans
- 来月、旅行することにしました。
- 新しい仕事を始めることにします。
- 来年はもっと勉強することにしよう。
Expressing personal resolutions
- 健康のために、運動することにしました。
- もっと親切にすることにしています。
- 無駄遣いをしないことに決めた。
In a meeting or discussion (as a proposal/agreement)
- この件は、後日検討することにしましょう。
- この方法で進めることにしました。
- 全員一致で、この案を採用することに決定しました。
Conversation Starters
"最近、何か新しいことを始めることにしましたか？"
"もし宝くじが当たったら、何にすることにしますか？"
"将来のために、今、何かすることにしていますか？"
"今日の夕食は何にすることにしましたか？"
"もし海外旅行に行けるなら、どこへ行くことにしますか？"
Journal Prompts
今日、あなたが決めたこと（〜ことにした）を３つ書いてみましょう。
将来、達成したい目標について、それを実現するために何をする（〜ことにする）か計画を立ててみましょう。
最近、何かをやめようと決めたこと（〜ないことにした）はありますか？その理由を書いてみましょう。
もしあなたがリーダーなら、チームのためにどのような決定（〜ことにする）をしますか？
Frequently Asked Questions
8 questionsGenerally, no. 〜ことにする emphasizes the speaker's personal decision. For decisions made by others, use verbs like 決める (kimeru) or 決定する (kettei suru).
〜ことにする is used for present or future decisions ('I will decide to...'), while 〜ことにした is the past tense, meaning 'I decided to...'.
Use the negative plain form of the verb followed by 〜ことにする. For example, 食べないことにする (tabenai koto ni suru) means 'decide not to eat'.
It can be used, but in very formal contexts (like official announcements), more formal verbs like 決定する (kettei suru) might be preferred. However, it's common in personal essays or reports detailing decisions.
While it emphasizes personal volition, it can be used to state your agreement or the outcome of a group decision, especially in the past tense (〜ことにしました) or as a suggestion (〜ことにしましょう).
'Koto' acts as a nominalizer, turning the preceding verb phrase (e.g., 'to go') into a noun-like concept ('the act of going') which can then be acted upon by 'suru' (to do).
〜ことにする is a firm decision ('I have decided to...'), whereas 〜ようにする implies an effort or attempt ('I will try to...' or 'I make sure to...').
Yes, depending on formality and nuance, you can use 決める (kimeru), 選択する (sentaku suru), or phrases like 〜べきだ (subeki da - should do).
Test Yourself
わたしは、明日、公園に ______ 。
The sentence is about a future decision, so '行くことにします' (decide to go) is the correct choice.
Which sentence means 'I decided not to buy the book'?
〜ないことにしました is used to express deciding *not* to do something.
The expression 〜ことにする is mainly used for decisions made by someone else.
〜ことにする specifically emphasizes the speaker's personal decision or resolution.
Word
Meaning
Matches the Japanese phrases with their English meanings.
Put the words in the correct order: 彼は / 会社を / 辞める / ことに / した
The correct order is '彼は会社を辞めることにした' (He decided to quit the company).
健康のために、もっと運動 ______ 。
'することにしました' indicates a firm decision made for health reasons. 'するようにしました' implies trying.
Which phrase best conveys a formal decision made after deliberation in a business context?
'〜ことに決定いたしました' is a highly formal way to state a decision, suitable for official business communication.
The expression 〜ことにする can be used to express a decision imposed by external authority.
The core meaning of 〜ことにする is personal volition and agency. Decisions imposed by authority are typically expressed using passive forms or verbs like 〜させる (saseru).
このえいがを ______ 。
The sentence requires the structure 'Verb (plain form) + ことにする' to express a decision to watch the movie.
What is the nuance difference between '〜ことにする' and '〜ようにする'?
〜ことにする signifies a resolved decision, while 〜ようにする indicates an effort or attempt to do something.
Score: /10
Summary
Use 〜ことにする to confidently state your personal decisions and resolutions.
- 〜ことにする means 'to decide to do'.
- It's attached to the plain form of a verb.
- Emphasizes personal volition and commitment.
- Used for present/future decisions (〜ことにします) and past decisions (〜ことにしました).
Connect 'Koto' to 'Quote'
Remember 'koto' as a 'quote' of your decision. You're quoting what you've decided to do. Then 'suru' means you're sure you'll do it!
Own Your Decisions
Native speakers use 〜ことにする to emphasize that the decision is *theirs*. Use it when you want to highlight your personal choice.
Personal vs. Group
While 〜ことにする is personal, 〜ことにしましょう is a great way to suggest a group decision politely. It balances personal choice with group harmony.
Plain Form Power
Always remember to use the plain form (dictionary, nai, ta) of the verb before 〜ことにする. Avoid polite forms like 〜ます.
Related Content
This Word in Other Languages
More daily_life words
じゅうしょ
A2The particulars of the place where someone lives.
住所
A2address, residence
～後
A2after
目覚まし
B1Alarm clock. A clock that makes a noise to wake someone up.
目覚まし時計
B1An alarm clock.
もう少し
B1A little more.
ひとりで
A2Alone.
~のに
B1Even though; despite (particle/conjunction).
ごぜん
A2Morning (a.m.).
煩い
B1Noisy; annoying.
