JLPT N2 grammar
〜たとたん（に） — Meaning & Examples
The instant X happened, (unexpectedly) Y — verb-た + とたん. Main clause must be past, real, and usually outside the speaker's control. ドアを開けたとたん、猫が飛び出した.
〜たとたん（に）— The Unexpected Instant-After
〜たとたん（に）= "the instant / the moment X happened, (unexpectedly) Y." This is the most common of the four and the one the exam tests most.
Formation: verb-た form + とたん（に）
ドアを開けたとたん、猫が飛び出してきた。
= The instant I opened the door, the cat came flying out.
立ち上がったとたんに、めまいがした。
= The moment I stood up, I felt dizzy.
彼女の顔を見たとたん、名前を思い出した。
= The instant I saw her face, I remembered her name.
Three hard rules for たとたん:
1. The main clause must be past tense and describe something that actually happened — often something the speaker witnessed or experienced, not caused on purpose.
❌ 家に着いたとたん、宿題をしよう。 (a plan — wrong)
2. No requests, commands, or invitations in the main clause.
❌ 授業が終わったとたん、帰ってください。 (a request — wrong)
3. The main clause is usually outside the speaker's control — a reaction, a coincidence, something that just occurred. "I opened the door and (on purpose) turned on the light" is plain 〜て, not たとたん.
とたん literally means "just then / that very moment" (途端 as a noun), which is why it feels so abrupt.
Practice questions
Try these 3 questions on 〜たとたん（に）. Pick an answer in your head, then open “Show answer”.
1. ドアを開けたとたん、猫が飛び出してきた means?
- I opened the door in order to let the cat out
- The instant I opened the door, the cat came flying out
- The cat opened the door
- I will open the door and the cat will come out
Show answer
Answer: The instant I opened the door, the cat came flying out
〜たとたん（に）= the instant X happened, (unexpectedly) Y. The main clause is a real past event outside the speaker's control.
2. Why is 「家に着いたとたん、宿題をしよう」 wrong?
- たとたん needs a noun before it
- The main clause is a plan/intention — たとたん needs a real past event
- 着く cannot take たとたん
- It should be 家に着いてから
Show answer
Answer: The main clause is a plan/intention — たとたん needs a real past event
たとたん cannot be followed by a plan, request, or intention. The second clause must describe something that actually happened, in the past.
3. ベルが鳴るか鳴らないかのうちに、彼は教室を飛び出した means?
- He left after the bell rang for a while
- The bell rang because he left
- He left before the bell
- The bell had barely started ringing when he shot out of the classroom
Show answer
Answer: The bell had barely started ringing when he shot out of the classroom
〜か〜ないかのうちに = X had barely happened / wasn't even finished when Y — even tighter than たとたん.
Practise 〜たとたん（に） in the free app
This point is part of the “⚡ Sudden Sequence — たとたん・かと思うと・か〜ないかのうちに・やいなや” lesson in A Star Japanese. Study it with examples, a quiz, flashcards and timed JLPT N2 mock exams. Free on iPhone and Android.
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Related N2 grammar points
From the same lesson: ⚡ Sudden Sequence — たとたん・かと思うと・か〜ないかのうちに・やいなや
- 〜かと思うと／かと思ったらNo sooner X than Y — often a rapid change or contrast (crying→laughing).
- 〜か〜ないかのうちにX had barely happened / wasn't even finished when Y — dict-form + か + ない-form + かのうちに.
- 〜やいなやThe very moment X, Y — literary/written register, same meaning as たとたん.
- たとたん vs 次第次第 = as soon as (planned, formal, the next clause is a future plan).
Frequently asked questions
What does 〜たとたん（に） mean?
The instant X happened, (unexpectedly) Y — verb-た + とたん. Main clause must be past, real, and usually outside the speaker's control. ドアを開けたとたん、猫が飛び出した.
Is 〜たとたん（に） on the JLPT N2 test?
〜たとたん（に） is taught in the JLPT N2 grammar course in A Star Japanese (lesson “⚡ Sudden Sequence — たとたん・かと思うと・か〜ないかのうちに・やいなや”), so it is a pattern learners at this level are expected to recognise. The JLPT does not publish an official grammar list, so treat this as a study guide rather than an official requirement.
How can I practise 〜たとたん（に）?
Open the “⚡ Sudden Sequence — たとたん・かと思うと・か〜ないかのうちに・やいなや” lesson in the free A Star Japanese app for iPhone and Android. It has examples, a quiz after every lesson, flashcards with spaced repetition and timed JLPT N2 mock exams, with no ads.