Expressing Change: なる and する

Expressing Change: なる

In this section, you will learn several key sentence patterns such as Japanese potential, passive, and causative form. We express various things by conjugating verbs. Since you have already completed Japanese basic grammar, all you need to do is to memorize conjugation patterns. Here, you will learn how to express change.

Explanation for How なる and する Work

Table of Contents
なる and する
ようになる and ようにする
ことになる and ことにする

You can express change in Japanese by using the two words なる (intransitive) and する (transitive). As you learned in the previous lesson, intransitive verbs don’t have objects while transitive verbs have objects. We will show you several functions of なる and する, but please keep the basic concept in mind.

なる and する

[わたしは / が] しゃ なった / なりました
[Topic / Subject] Target Verb
[I] became a doctor.
[わたしは / が] ども しゃ する / します
[Topic / Subject] Direct Object Target Verb
[I] will make [my] child a doctor.

Both なる and する can express change of states. The difference is that なる indicates your state alone will change like “to become” while する indicates someone will change your state like “to make it something.” The target of change is expressed by the particle に.

来年らいねん20歳はたちに(なる / なります)。
Next year, [I] will become 20 years old.
ポケモンは有名ゆうめいに(なった / なりました)。
Pokemon became famous.
部屋へやをきれいに(する / します)。
[I] will make [my] room clean.
ことづかいを丁寧ていねいに(した / しました)。
[I] made [my] wording polite.

When you connect i-adjectives, you don’t add the particle に, but conjugate them: to replace い with く.

いぬおお(なる / なります)。
Puppies become big.
すず(なった / なりました)。
[It] has become cool.
カレーをあたた(する / します)。
[I] will make the curry warm.
だんやす(した / しました)。
[I] made the price cheap.

Here is a special expression. You can connect even verbs. However, verbs have to be the negative form. This doesn’t also require the particle に, but you need to replace the last い with く, that is to say, the same conjugation as the one for i-adjectives.

どもかな(なる / なります)。
Lit. Children become the ones that won’t cry (children don't cry anymore).
ケーキをべな(なった / なりました)。
Lit. [I] became the ones that wouldn’t eat cake (I don't eat cake anymore).
アラームをらな(する / します)。
[I] will make it so that the alarm won’t ring.
カレーをめな(した / しました)。
[I] made it so that the curry wouldn't get cold.

As you learned, ない, which is the negative form of “ある: to be, to exist,” is an exception. When you connect ない with なる and する, it will work differently from other verbs. In present and future tense, you need to drop る.

よく携帯けいたいがな(なる / なります)。
[My] mobile is often lost.
かさがな(なった / なりました)。
[My] umbrella was lost.
よくわたし携帯けいたいをな / します)。
I often lose [my] cell phone.
かさをな(した / しました)。
[I] lose [my] umbrella.

There is one common set phrase. When you use する with products, it means to order like “I will have coke.”

わたしはコーラに(する / します)。
I will have coke.
ぼくはこれに(する / します)。
I will have this one.

ようになる and ようにする

[わたしは / が] 運動うんどうをよくするように なった / なりました
[Topic / Subject] Target Verb
Lit. [I] became the one that often did exercises.
(I came to the point that I often did exercises).

When you connect the affirmative form of verbs with なる and する, you need to apply another conjugation, which is ように. For the sake of simplicity, you may consider 運動うんどうをよくするように as a noun phrase. Just like the above, ようになる indicates that your state will change alone.

どもはたらくように(なる / なります)。
Lit. Children will become the ones that work, too. (*reach the point that they start working).
しょうせつむように(なった / なりました)。
[I] became the one that read novels.
[わたしは / が] 運動うんどうをよくするように した / しました
[Topic / Subject] Target Verb
[I] made it so that [I] often did exercises.

ようにする indicates someone will change your state and often expresses customary actions. With the above example, after that, it must be true that you continuously did exercises for a certain time. Depending on the contexts, it can imply your level of effort. For example, the third example below implies your effort while the fourth one doesn't. 

はやきるように(する / します)。
[I] will make it so that [I] get up early.
べんきょうをたくさんするように(した / しました)。
[I] made it so that [I] studied a lot.
悪口わるぐちわないように(した / しました)。
[I] made it so that [I] wouldn't speak critically.
悪口わるぐちわな(した / しました)。
[I] made it so that [I] wouldn't speak critically.
[わたしは / が] かぜ部屋へやはいるように した / しました
[Topic / Subject] Target Verb
[I] made it so that the wind comes into [my] room.

ようにする has another function, which is to make something happen. Unlike the first function, you took the action for just one time. With the example above, you maybe did something like opening a window.

テレビをうごくように(する / します)。
[I] will make it so that the TV works.
クーラーで部屋へやえるように(した / しました)。
[I] made it so that the room would get cold by the air conditioner.

ことになる and ことにする

[わたしは / が] えいべんきょうすることに なった / なりました
[Topic / Subject] Target Verb
It was decided that [I] would study English.
[わたしは / が] えいべんきょうすることに した / しました
[Topic / Subject] Target Verb
[I] decided that [I] would study English.

The function here is to express decisions. ことになる indicates that decisions are naturally or situationally made, e.g. a teacher gives you a compulsory class. By contrast, ことにする indicates that decisions are made by you.

ドイツにすことに(なる / なります)。
It will be decided that [I] will move to Germany.
 毎日まいにちほんむことに(なった / なりました)。
It was decided that [I] read books every day.
ドイツにすことに(する / します)。
[I] will decide that [I] will move to Germany.
毎日まいにちほんむことに(した / しました)。
[I] decided that [I] read books every day.

If you replace に with と, your speech will sound more formal.

ドイツにすこと(なる / なります)。
毎日まいにちほんむこと(した / しました)。

You may wonder about how “める: to decide” and “まる to be decided” work. They are the verbs which express decisions. You can just replace them.

ドイツにすことに(まった / まりました)。
毎日まいにちほんむことに(めた / めました)。

ことにする is also interchangeable with ようにする which expresses customary actions. Note: you cannot use another function which is to make something happen. The following examples essentially have the same meaning.

毎日まいにちほんことに(した / しました)。
[I] decided that [I] read books every day.
毎日まいにちほんように(した / しました)。
[I] made it so that [I] read books every day.

In practice, even if you made a decision, you can use ことになる. When you have something that you would like to indirectly express, you can avoid disclosing who made the decision. For example, if you own a company and decide that the company will go bankrupt, you still say the following.

会社かいしゃ倒産とうさんすることに(なった / なりました)。
It has been decided that the company will go bankrupt.


  1. なる doesn’t have objects. Your state alone will change.
  2. する has objects. Someone will change your state.
  3. Nouns and na-adjectives require に to express targets of change.
  4. I-adjectives and the negative form of verbs don't need に, but to replace い with く.
  5. With the affirmative form of verbs, the conjugation is to add ように.
  6. ことにする / なる expresses decisions.

We believe this topic is not too complicated. If you have difficulty understanding the concept, we recommend you review the lesson about transitive verbs and intransitive verbs. Then, if you would like to say “I’ve become able to speak Japanese,” how should it be? This sentence indicate change of your potential. Next, you will learn Japanese potential form.