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The Most Useful Japanese Grammar : Adj + する

In Japanese, we often use 「Adjective + する」 to express “to make something ~” or “to become ~.”
It’s a useful and natural pattern in daily conversation!


1. What It Means

Let’s talk about what it means. When we attach する to an い-adjective or な-adjective, it means “to make (something) ~” or “to make it become ~.”
In English, this is like saying “make it clean,” “make it quiet,” “make it simple,” etc.

2. How to Form It

🟢 For い-adjectives:

Remove and add くする

い-Adjective → くする

Examples:

  • たかい → たかくする
  • (make it expensive / raise the price)
  • はやい → はやくする
  • (make it fast / hurry up)
  • あたらしい → あたらしくする
  • (make it new / renew)

🟣 For な-adjectives:

Add にする after the adjective

な-Adjective → にする

Examples:

  • きれい → きれいにする
  • (make it clean / tidy up)
  • しずか → しずかにする
  • (make it quiet)
  • 簡単かんたん簡単かんたんにする
  • (make it simple)

3. Example Sentences

  • 部屋へやきれいにしました
  • → I cleaned the room. (I made the room clean.)
  • おとちいさくしてください
  • → Please make the sound smaller (turn down the volume).
  • ふくあたらしくしたいです。
  • → I want to make (my) clothes new / get new clothes.
  • もっとしずかにしてください
  • → Please be quieter.
  • 値段ねだんやすくします
  • → I’ll make the price cheaper.

4. Adjective + なる vs Adjective + する

Be careful because it might be easy to mix up なる and する, but the difference is simple:

PatternMeaningFocusExample
Adjective + なるto become ~change happens naturallyきれいになる → become clean
Adjective + するto make ~you cause the changeきれいにする → make (something) clean

🪄 Think of なる as “it becomes” and する as “I make it become.”


🧠 Practice Time

Try to make sentences using Adjective + する!

  1. I make your room clean → __________
  2. Please make the sound smaller → __________
  3. They made the price cheaper → __________
  4. Let’s make the color bright → __________
  5. Make the explanation simple → __________
  6. Make your hair long → __________
  7. We should make the food spicy → __________
  8. I want to make my team stronger → __________
  9. Make the room quiet → __________
  10. Make the story interesting → __________

✅ Answers:

  1. 部屋へやをきれいにする
  2. おとちいさくしてください
  3. 値段ねだんやすくしました
  4. いろあるるくしましょう
  5. 説明せつめい簡単かんたんにする
  6. かみを長くする
  7. 食べ物をからくするべきです
  8. チームを強くしたい
  9. 部屋を静かにする
  10. 話をおもしろくする

I hope this post helps! Feel free to let us know in the comment if you have any questions!

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