他動詞 / 自動詞【たどうし / じどうし】

Japanese verbs can be divided into 他動詞 (transitive verbs) and 自動詞 (intransitive verbs). Understanding the difference is essential for expressing whether someone performs an action on something or whether something happens on its own.

他動詞 – Transitive verbs

A 他動詞 requires a doer (subject) who acts on an object. The object is marked with を.

Here, I am the one who performed the action of opening.

自動詞 – Intransitive verbs

A 自動詞 describes something that happens by itself or focuses on a change of state without emphasizing who caused it. The subject is typically marked with が.

Here, the door opened – no one in particular is mentioned as the cause.

Common transitive / intransitive pairs

Many Japanese verbs come in pairs that share the same kanji but have different endings:

• あける開ける (あける・他動詞) / ひらく開く (あく・自動詞) – to open
• しめる閉める (しめる・他動詞) / しまる閉まる (しまる・自動詞) – to close
• つける (他動詞) / つく (自動詞) – to turn on / attach
• けす消す (けす・他動詞) / きえる消える (きえる・自動詞) – to turn off / extinguish
• こわす壊す (こわす・他動詞) / こわれる壊れる (こわれる・自動詞) – to break
• おとす落とす (おとす・他動詞) / おちる落ちる (おちる・自動詞) – to drop
• いれる入れる (いれる・他動詞) / はいる入る (はいる・自動詞) – to put in / to enter
• だす出す (だす・他動詞) / でる出る (でる・自動詞) – to take out / to come out
• はじめる始める (はじめる・他動詞) / はじまる始まる (はじまる・自動詞) – to start

Particle patterns

The key difference in sentence structure is the particles used:

• 他動詞: Subject は/が + Object を

  • 他動詞
  はは母がでんき電気をつけた。

  My mother turned on the light.

• 自動詞: Subject が

  • 自動詞
  でんき電気がついた。

  The light turned on.

Choosing between 他動詞 and 自動詞

Use a 他動詞 when you want to emphasize who did it or intentional action:

Use a 自動詞 when the cause is unknown, unimportant, or natural:

This distinction is especially important with 〜～ている. With 他動詞, ～ている often means an action is ongoing. With 自動詞, ～ている often describes a resulting state: