English uses one word for both sides of many events: "the door opens" and "I open the door" share open. Japanese usually splits these into a pair — an intransitive verb (自動詞, something happens by itself) and a transitive verb (他動詞, someone does it to something). Picking the wrong half is one of the most common and most audible beginner mistakes.
The core idea
An intransitive verb describes a change or action with no doer acting on something — the thing itself is the subject, marked が, and there is no を object. A transitive verb has an agent doing it to a direct object, marked を.
| Japanese | Reading | Meaning |
|---|---|---|
| ドアが開く | doa ga aku | the door opens (自動詞) |
| ドアを開ける | doa o akeru | I open the door (他動詞) |
| 電気が消えた | denki ga kieta | the light went out (自動詞) |
| 電気を消した | denki o keshita | I turned the light off (他動詞) |
Why it matters
Three reasons this isn't optional trivia. First, it fixes whether you use が or を — get the verb wrong and the particle is wrong too. Second, it changes what 〜ている means (next section). Third, using a transitive verb with no agent (or an intransitive with を) sounds, to a native ear, roughly like "the door was opening itself by me" — instantly off.
Common pairs
There's no shortcut around learning these as pairs. The good news: they share a kanji and usually a vowel pattern, so they cluster in memory. The high-frequency set:
| Meaning | Intransitive (が) | Transitive (を) |
|---|---|---|
| open | 開く (aku) | 開ける (akeru) |
| close | 閉まる (shimaru) | 閉める (shimeru) |
| begin | 始まる (hajimaru) | 始める (hajimeru) |
| stop | 止まる (tomaru) | 止める (tomeru) |
| enter / put in | 入る (hairu) | 入れる (ireru) |
| exit / take out | 出る (deru) | 出す (dasu) |
| turn on / attach | 付く (tsuku) | 付ける (tsukeru) |
| disappear / erase | 消える (kieru) | 消す (kesu) |
| fall / drop | 落ちる (ochiru) | 落とす (otosu) |
| break | 壊れる (kowareru) | 壊す (kowasu) |
| change | 変わる (kawaru) | 変える (kaeru) |
| be decided / decide | 決まる (kimaru) | 決める (kimeru) |
The patterns (loose, not rules)
You'll notice tendencies: an 〜ある ending is often intransitive (閉まる, 始まる), an 〜える ending often transitive (閉める, 開ける), and an 〜す ending is reliably transitive (出す, 消す). These help you guess — but there are enough exceptions that you should treat them as hints, not laws. Learn the pair; let the hint speed up recall.
〜ている and 〜てある
This is where transitivity pays off. An intransitive verb plus ている describes the resulting state: 窓が開いている = "the window is open." A transitive verb plus ている is the action in progress: 窓を開けている = "[someone] is opening the window."
Separately, a transitive verb plus てある describes a state someone deliberately produced and left — 窓が開けてある = "the window has been (intentionally) opened." Note it takes が for the affected thing even though the verb is transitive.