～にする

The structures ～くする and ～にする are used to express making something or someone become a certain way. The form you use depends on the type of adjective.

い-adjectives: ～くする

For い-adjectives, drop the final い and add くする. This means "to make (something) more ~."

な-adjectives: ～にする

For な-adjectives, attach にする to the adjective stem. This means "to make (something) ~."

Nouns: ～にする

With nouns, にする can mean "to make (something) into ~" or "to decide on ~."

Key points

• The object being changed is typically marked with を, but when describing your own state or behavior, the を is sometimes omitted (e.g. しずかに静かにする).
• These forms can be conjugated like any other verb: past (おおきく大きくした), negative (おおきく大きくしない), て-form (おおきく大きくして), polite (おおきく大きくします), etc.
• Do not confuse ～くする / ～にする (intentional action – "to make ~") with ～くなる / ～になる (natural change – "to become ~").
  かみ髪をみじかく短くした。

  I made my hair short. (I cut it.)
  かみ髪がみじかく短くなった。

  My hair became short. (It got shorter.)