ことにする
Decide to
ことにする is used when you have made a deliberate choice to do (or not do) something. It emphasizes your own will and agency in the decision-making process.
How It Works
The expression ことにする is a fundamental way to talk about intentions and resolutions in Japanese.
1. Personal Decisions:
It indicates that the speaker has looked at various options and actively chosen one path. While つもり expresses an intention, ことにする feels more like a finalized decision.
2. Negative Decisions:
To decide not to do something, you attach it to the negative form of the verb (e.g., 行かないことにした - I decided not to go).
3. Habitual Rules (~ことにしている):
When used in the te-iru form, it describes a habit or a rule you have set for yourself. For example, 'I make it a rule to exercise every day.'
4. The 'Pretend' Nuance (~たことにする):
When used with the past tense, it can mean 'to pretend' or 'to act as if' something happened (or didn't happen).
5. Comparison with ことになる:
While ことにする is an internal decision ('I decided'), ことになる is used for external decisions ('It has been decided' by someone else or by circumstances).
Examples (4)
- 健康のために、毎日野菜を食べることにしました。
I have decided to eat vegetables every day for my health.
Word by Word: Health for-the-sake-of, every day vegetables (object) eat decide-did.
This shows a deliberate personal decision to improve one's lifestyle.
- 高いから、新しいパソコンは買わないことにした。
Since it's expensive, I decided not to buy a new computer.
Word by Word: Expensive because, new computer (object) buy-not decide-did.
Here, the negative form (買わない) is used to show a decision to refrain from an action.
- 今の話は聞かなかったことにしてください。
Please pretend you didn't hear what I just said.
Word by Word: Now's talk (topic) hear-did-not fact-to do please.
Using the past tense (聞かなかった) creates the nuance of 'acting as if' something didn't happen.
- 寝る前にスマホを見ないことにしている。
I make it a rule not to look at my smartphone before going to bed.
Word by Word: Sleep before smartphone (object) look-not decide-doing-am.
The ~ている form indicates a continuous self-imposed habit or rule.
Common Mistakes
Using 'koto ni naru' for personal decisions.
私は日本に行くことになりました。私は日本に行くことにしました。If you personally chose to go, use 'suru'. Using 'naru' implies the decision was made for you by your company, school, or fate.
Negating 'suru' instead of the verb to mean 'decided not to'.
行くことにしませんでした。行かないことにしました。'Koto ni shinai' means 'I won't make a decision to...', which is rarely used. To say 'I decided not to go', you must negate the verb before 'koto'.
How It Connects
Learn This First
To understand 'ことにする', you need to know how to turn a verb into a noun phrase using a nominalizer (like 'こと'), how the particle 'に' marks a result or choice, and the basic rules for modifying a noun with a verb.
- のPossessive/nominalizer
The pattern uses the nominalizer 'こと' (which functions similarly to 'の') to turn a verb phrase into a noun clause so it can be followed by a particle.
Level 1 - にTarget/location Marker
The particle 'に' is used here to indicate the result of a choice or transformation, which is essential for the 'decide on' meaning.
Level 1 - Noun Modification
Understanding how verbs modify nouns is necessary because the verb phrase precedes and modifies the noun 'こと'.
Level 1
Related Patterns
- ことになるIt's Been Decided
Expresses a decision made by external factors or circumstances rather than the speaker's own will.
Level 3 - ことにしているMake a Habit of
The habitual version of this pattern, used for self-imposed rules and routines.
Level 2 - ようにするTry To/make Sure to
Indicates making an effort to do something, whereas 'koto ni suru' is a firm decision.
Level 2 - つもりIntend to
Expresses an intention or plan, which may be less finalized than a 'koto ni suru' decision.
Level 2 - ことVerb to Noun
The base nominalizer used to turn the preceding verb into a noun phrase so it can be 'acted upon' by the verb 'suru'.
Level 3
Words in This Pattern
Practice ことにする in Bubblegum
Poppy, your AI tutor, writes Japanese lessons at your level. Tap any grammar point in a lesson to see its full explanation.
