〜にする: Deciding On, Choosing, and Making Things a Certain Way
Two jobs, one pattern
〜にする carries one core feeling — you make the choice — and it does two related jobs with it. First, you pick from options: attach にする to the noun you've settled on. Second, you deliberately change something into a particular state. In both cases a person decides, and that person makes it so.
The attachment is simple. にする hooks onto 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 |
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.
Announcing your pick
This is the version you'll use most — at a café, a shop, anywhere with a menu. You're announcing your choice, and the thing you land on takes に, never を: it's コーヒーにします, not コーヒーをします. When you're choosing "the ~ one," slot の in after an い-adjective to stand in for the noun — 赤いのにする, 小さいのにする.
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.
Steering something into a state
The other job is saying someone deliberately changes a state. The classic example is 静かにする — "be quiet," literally "make (it) quiet." Whatever you're acting on takes を, because you're doing something to it: 教室をきれいにする, 部屋を静かにする.
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 or になる — is anyone steering?
These two look alike but mean opposite things, and the whole difference is whether a person is at the wheel:
- 〜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 simply occurs, use なる. This is the slip learners make most — picking する when nothing is actually being done to cause the change. 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.
The short version
- 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.
Practice it
Choose the correct use of にする (deciding) vs になる (becoming).
＿＿＿に入れるのに最もよいものを選びなさい。
Choose the grammar pattern that best completes the sentence.
ヤッタンはコーヒー＿＿＿。
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.
Where 〜にする fits
Once this clicks, go on to
- 〜ようにする · N4 — 〜ようにする means making a conscious effort to do (or not do) something — 'try to / make sure to.' Learn the formation, the negative, the ている habit form, and how it differs from ようになる.
Hear it in a real conversation
See this pattern used naturally in a real-situation dialogue:
More N5 grammar to explore
Keep going with related patterns at the same level:
- 〜のが上手 / 〜のが下手 — 上手 (good at) and 下手 (bad at) are な-adjectives. Learn NOUNが上手, VERBのが上手, the が vs を trap, and why you shouldn't call yourself 上手.
- 〜のが好き — 好き means 'like': a thing takes が (音楽が好き). To like doing something, nominalize the verb with の: 読むのが好き. Learn the formation, 大好き/嫌い, and common particle mistakes.
- Past Tense — The plain past た-form means 'did.' It follows the same sound changes as the て-form (just て→た, で→だ): 食べた, 行った, 飲んだ. Learn it by verb group.
- 〜たことがある — 〜たことがある means you have done something before — 日本に行ったことがある. Learn the past-form formation, the negative 〜たことがない (have never), and how it differs from the plain past.
- 〜てみてください — 〜てみる means to do something and see how it goes (try it out). Add ください for 〜てみてください — a friendly 'please give it a try.' Learn the form, conjugations, and casual 〜てみて.
- 〜と一緒に — 〜と一緒に means doing something 'together with' someone: 家族と一緒に旅行する. Learn the pattern, why と marks the companion, when 一緒に stands alone, and how it differs from plain と.