connective N3 common casualpolitewritten
〜たとたん — the instant ~ / the moment ~
〜たとたん ・ たとたん
Builds on た形
Meaning
- the instant ~ / the moment ~ — right as one action finished, a second (often unexpected) thing happened
たとたん (途端 = 'the very moment') marks an abrupt, often surprising sequence: the second event follows the first instantly and beyond the speaker's control. 立ち上がったとたん、めまいがした ('the instant I stood up, I felt dizzy'). Both clauses are past and factual — it describes what *did* happen, so it can't be used for commands, requests, or intentions in the second clause.
Key sentence
ドアを開けたとたん、猫が飛び出した。
The instant I opened the door, the cat shot out.
Formation
| Attaches to | Form | Example |
|---|---|---|
| Verb た-form + とたん(に) | Vた + とたん(に) | 見たとたん / 帰ったとたん |
Examples
家を出たとたん、雨が降り出した。
The moment I left the house, it started to rain.
電気を消したとたん、物音がした。
The instant I turned off the light, there was a noise.
彼は座ったとたん、眠ってしまった。
The moment he sat down, he fell asleep.
Easily confused with
たらすぐ たらすぐ = 'as soon as', and the second clause can be planned (帰ったらすぐ電話して, 'call as soon as you get back'); たとたん is a past, often *unexpected* happening — no commands or intentions allowed. 〜なり Both mark an instant sequence; なり is more literary and stresses one subject doing B straight off (見るなり泣き出した), while たとたん highlights a sudden, often surprising result and is the everyday choice.
Notes
- とたんに (with に) is interchangeable. The surprise/abruptness is core — a smoothly expected next step uses たら/と instead.
See 〜たとたん in real sentences
Jengo shows 〜たとたん the way you actually meet it: inside real Japanese sentences, so it sticks instead of staying an abstract rule.
Study it in Jengo