〜にする: Deciding On, Choosing, and Making Things a Certain Way
What it means
〜にする has one core feeling: you make the choice. When you pick from options — what to order, which one to buy — you attach にする to the noun you've settled on. The same pattern describes deliberately changing something into a particular state. In both cases a person decides, and that person makes it so. Compare this with なる ("become"), which describes change that happens by itself.
ヤッタンはコーヒーにします。
ヤッタンは コーヒーに します。
Yattan will have coffee.
にします after the noun = I'll go with / I'll have this one.
モチは赤いのにした。
モチは あかいのに した。
Mochi decided on the red one.
の stands in for the noun ('the red one').
先生は部屋をきれいにしました。
せんせいは へやを きれいに しました。
The teacher made the room clean.
Deliberate change: someone tidied it.
How to form it
にする attaches to a noun or a な-adjective. For "make X into Y," X takes を and Y takes に.
| What you're saying | Pattern | Example |
|---|---|---|
| Choose / decide on (noun) | Noun + にする | コーヒーにする (I'll have coffee) |
| Choose "the ~ one" | い-adj + の + にする | 赤いのにする (I'll take the red one) |
| Make X a certain way (な-adj) | X を + な-adj + にする | 部屋をきれいにする (make the room clean) |
| Make X a certain way (noun) | X を + Noun + にする | 弟をリーダーにする (make my brother leader) |
| Past / polite | にした / にします | コーヒーにしました |
Ordering and choosing
This is the version you'll use most — at a café, a shop, anywhere with a menu. You're announcing your pick.
私はラーメンにします。
わたしは ラーメンに します。
I'll have ramen.
ヤッタンはどれにしますか。
ヤッタンは どれに しますか。
Which one will you have, Yattan?
どれにする = 'which will you go with?'
モチは小さいのにしました。
モチは ちいさいのに しました。
Mochi went with the small one.
Making something a certain way
Use にする to say someone deliberately changes a state. The classic example is 静かにする — "be quiet," literally "make (it) quiet."
ヤッタンの弟、静かにして。
ヤッタンの おとうと、しずかに して。
Yattan's little brother, be quiet.
静かにして = make it quiet → 'quiet down.'
先生は教室をきれいにします。
せんせいは きょうしつを きれいに します。
The teacher makes the classroom clean.
にする vs なる — who makes the change?
These two look similar but mean opposite things. Keep the doer in mind:
- 〜にする = someone makes it so / decides it. 部屋を静かにする = "make the room quiet" (a person does it).
- 〜になる = it becomes so on its own, naturally. 部屋が静かになる = "the room becomes quiet" (it just happens).
So 元気にする is "make someone cheerful," while 元気になる is "get better / become cheerful." If a person is deliberately causing the change, reach for にする. If the change just occurs, use なる. There is also a related advanced pattern, 〜ようにする ("make an effort to do / try to"), which uses this same "make it so" idea with a verb.
Common mistakes
- Using を instead of に for your choice. The thing you pick takes に: コーヒーにします (✓), not コーヒーをします.
- Mixing up する and なる. 静かにする = make it quiet (someone acts); 静かになる = it becomes quiet by itself. Choose by who causes the change.
- Forgetting を on the changed object. In "make X into Y," X needs を: 部屋をきれいにする (✓).
- Dropping の after an い-adjective. "The red one" is 赤いのにする — you need の to stand in for the noun.
Quick recap
- にする = decide on / choose: コーヒーにします ("I'll have coffee").
- "The ~ one" → い-adjective + の + にする: 赤いのにする.
- "Make X a certain way" → Xを + な-adj/noun + にする: 部屋をきれいにする.
- する = someone makes it happen; なる = it happens on its own.
Your turn
Choose the correct use of にする (deciding) vs になる (becoming).
Start the 5-question drill →Frequently asked questions
What does コーヒーにします mean?
It means 'I'll have coffee.' にする after a noun is how you announce your choice from options, like ordering at a café. The thing you pick takes に, not を.
What's the difference between にする and になる?
にする means someone deliberately makes or decides something: 静かにする ('make it quiet'). になる means something becomes so on its own: 静かになる ('it becomes quiet'). The difference is whether a person causes the change.
How do I say 'the red one' with にする?
Use の to stand in for the noun: 赤いのにする ('I'll take the red one'). The の replaces the thing you're choosing, so you don't repeat the noun.
Why is it 部屋をきれいにする and not 部屋がきれいにする?
When you make X into a certain state, X takes を because you're acting on it: 部屋をきれいにする ('make the room clean'). The resulting state (きれい) connects with に before する.