他動詞 & 自動詞【たどうし & じどうし】

In Japanese, verbs are classified as either 他動詞 (transitive verbs) or 自動詞 (intransitive verbs). Understanding this distinction is essential because it affects which particles you use and how sentences are structured.

他動詞 – Transitive verbs

A 他動詞 describes an action that someone or something does to an object. It requires a doer (marked by が) and an object (marked by を).

The focus is on who does the action and what is affected.

自動詞 – Intransitive verbs

A 自動詞 describes something that happens on its own or a change of state, without implying a specific doer acting on an object. The subject is typically marked by が.

The focus is on what happens, not on who caused it.

Common transitive / intransitive pairs

Many Japanese verbs come in pairs that share the same kanji but have different endings. Here are some of the most common:

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

Particle patterns

The key difference in sentence structure is:

• 他動詞: 〜が 〜を V（他動詞）
• 自動詞: 〜が V（自動詞）

With ～ている

When combined with ～ている, transitive and intransitive verbs often convey different nuances:

• 他動詞 + ている tends to describe an ongoing action.

  かれ彼がどあドアをあけている開けている。

  He is opening the door (right now).

• 自動詞 + ている tends to describe a resulting state.

  どあドアがひらいている開いている。

  The door is open (as a result of being opened).

This is one of the most common areas where learners make mistakes. For example, to say "the window is open," you should use the intransitive form:

Using the transitive form まど窓をあけている開けている would mean "someone is in the process of opening the window."

Choosing between 他動詞 and 自動詞

Use 他動詞 when you want to emphasize who did something or what someone did to something. Use 自動詞 when you want to describe what happened without focusing on the cause or agent. Japanese often prefers 自動詞 in everyday descriptions of states and events, which is why phrases like でんき電気がついている ("the light is on") are much more natural than saying who turned it on.