Becoming なる/する in Japanese

Overview

Japanese expresses change with two key verbs: なる (naru, to become) and する (suru, to make/decide). なる describes natural or spontaneous change — things that become different on their own or over time. する describes deliberate change — things that someone actively makes different or decides on. Together, they cover the full spectrum of change, from weather shifting to conscious decisions.

This is an A2 concept that adds depth to your descriptions. Instead of saying "it is warm," you can say "it became warm." Instead of "the room is clean," you can say "I made the room clean." This ability to describe change and transformation is fundamental to natural Japanese.

How It Works

なる (become) — natural/spontaneous change

Word type	Form + なる	Example	Meaning
い-adjective	Drop い, add くなる	暖かくなる	become warm
な-adjective	Stem + になる	静かになる	become quiet
Noun	Noun + になる	医者になる	become a doctor

する (make/decide on) — deliberate change

Word type	Form + する	Example	Meaning
い-adjective	Drop い, add くする	大きくする	make bigger
な-adjective	Stem + にする	きれいにする	make clean
Noun	Noun + にする	コーヒーにする	decide on coffee

Summary pattern

Change type	い-adj	な-adj	Noun
Become (natural)	~くなる	~になる	~になる
Make (deliberate)	~くする	~にする	~にする

Examples in Context

Japanese	English	Note
暖かくなりました。	It became warm.	Weather change (なる)
医者になりたいです。	I want to become a doctor.	Career goal (なる)
部屋をきれいにしました。	I made the room clean.	Deliberate action (する)
コーヒーにします。	I'll have coffee.	Decision (にする)
日本語が上手になりましたね。	Your Japanese has gotten good!	Compliment (なる)
テレビの音を小さくしてください。	Please turn the TV volume down.	Request (する)
最近、寒くなりましたね。	It's gotten cold recently, hasn't it?	Seasonal change
髪を短くしました。	I made my hair short. (I got a haircut.)	Personal change (する)
大人になったら何になりたいですか？	What do you want to be when you grow up?	Double なる
部屋を暗くしないでください。	Please don't make the room dark.	Negative request
だんだん暑くなります。	It gradually gets hotter.	Gradual change
静かにしてください。	Please be quiet.	Common request (する)

Common Mistakes

Confusing the adjective forms

• Wrong: 暖かいになりました。
• Right: 暖かくなりました。
• Why: い-adjectives use the く form before なる/する. Drop the い and add く. な-adjectives use に.

Using なる when する is needed (and vice versa)

• Wrong: 部屋をきれいになりました。 (intending "I cleaned the room")
• Right: 部屋をきれいにしました。
• Why: If someone deliberately caused the change, use する. なる implies the change happened naturally. 部屋がきれいになりました (the room became clean — by itself or unspecified) is grammatically fine but has a different meaning.

Forgetting を with する and が with なる

• Wrong: 音が大きくしてください。
• Right: 音を大きくしてください。
• Why: With する (deliberate change), the thing being changed takes を. With なる (spontaneous change), it takes が: 音が大きくなりました (the sound got louder).

Mistranslating にする as only "become"

• Wrong: Thinking コーヒーにします means "I become coffee"
• Right: It means "I'll go with coffee" or "I'll have coffee"
• Why: Noun + にする has a special meaning of "decide on" or "choose." This is extremely common when ordering food or making selections.

Usage Notes

The にする pattern for decisions is one of the most common phrases in daily life. At restaurants: 私はラーメンにします (I'll have ramen). When choosing: これにします (I'll go with this one). It is casual but perfectly polite with します.

なる + たい (want to become) is how you express career ambitions and life goals: 先生になりたい (I want to become a teacher). This combination is very common from A2 onward.

だんだん (gradually) and どんどん (rapidly) pair naturally with なる to describe the pace of change: だんだん暖かくなります (it gradually gets warmer).

Practice Tips

• Describe seasonal changes using なる: 春になると暖かくなります, 秋になると涼しくなります. This is natural, conversational Japanese.
• Practice ordering at imaginary restaurants using にする: 何にしますか？ — カレーにします.
• For deliberate changes, think about things you adjust in daily life: volume, temperature, brightness. Express each with する.

Related Concepts

• Prerequisite: Adjectives as Adverbs — the く/に forms used with なる/する