Two Sides of Every Change
Japanese often has two verbs for one event: one where something changes by itself, and one where somebody changes it. English usually manages with one verb plus a pronoun; Japanese uses a different verb and a different particle.
The intransitive verb describes a change of state and takes が. The transitive verb describes an action on an object and takes を. Choosing the wrong one is one of the most noticeable errors a learner can make.
The Pairs Worth Learning
These fifteen pairs cover most everyday situations and appear constantly in exams.
Often a person is the giveaway
Intransitive sentences usually have no person doing anything — the event happens. If a person appears with を, the verb is transitive: 私は電気を消した, not 電気が消した.The Shape Patterns
The pairs are not random. Most follow one of four morphological patterns, and knowing them lets you guess a pair you have never seen.
The most productive is -aru / -eru: 上がる・上げる, 下がる・下げる, 変わる・変える, 集まる・集める. If a verb ends in -aru, its partner almost certainly ends in -eru.
ている: State or Action?
This is where the distinction becomes genuinely useful. With an intransitive verb, ている describes a resulting state. With a transitive verb, it describes an action in progress.
てある: deliberate resulting state
Transitive verb + てある describes a state that exists because someone did something on purpose.
Compare the three: 窓が開いている (just a state), 窓を開けている (someone is doing it now), 窓が開けてある (deliberately left open).
How to Memorise Them
One scene, three sentences
Take a door and write: ドアが開いた / ドアを開けた / ドアが開いている. Say them aloud until the particles come automatically. Repeat with a light, a window and a car.
Common Mistakes
Practice
Choose the correct verb and particle.
- 電車が（止まった / 止めた）。
- 私は電気を（ついた / つけた）。
- 会議は九時に（始まった / 始めた）。
- かばんが（見つかった / 見つけた）。
- 彼は窓を（開いている / 開けてある）。
For the verb forms themselves, see Japanese verb conjugation. For the particles that go with each type, read は vs が.
FAQ
What is the difference between 自動詞 and 他動詞?
自動詞 are intransitive verbs describing a change that happens by itself, taking が: 窓が開いた. 他動詞 are transitive verbs describing someone acting on an object, taking を: 窓を開けた.
How many transitive-intransitive pairs are there?
There are several hundred pairs in common use, but roughly fifty cover everyday Japanese and the levels up to N3. Around fifteen to twenty are frequent enough that you should know them without thinking.
Why does ている sometimes mean "is" and sometimes "is doing"?
Because the meaning depends on the verb type. With intransitive verbs, ている describes a resulting state (窓が開いている = the window is open); with transitive verbs it describes an action in progress (窓を開けている = someone is opening the window).
Is there a rule for which verb is transitive?
The most useful pattern is -aru for intransitive and -eru for transitive: 上がる / 上げる, 変わる / 変える, 集まる / 集める. Other patterns exist (-ru / -su, -eru / -asu) and are worth learning as groups.