JLPT N2 grammar
たとたん vs 次第 — Meaning & Examples
次第 = as soon as (planned, formal, the next clause is a future plan). たとたん = the instant (unexpected, past, a real event that surprised the speaker). Opposite direction in time.
〜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 vs 次第. 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 vs 次第 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
- 〜たとたん（に）The instant X happened, (unexpectedly) Y — verb-た + とたん.
- 〜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.
Frequently asked questions
What does たとたん vs 次第 mean?
次第 = as soon as (planned, formal, the next clause is a future plan). たとたん = the instant (unexpected, past, a real event that surprised the speaker). Opposite direction in time.
Is たとたん vs 次第 on the JLPT N2 test?
たとたん vs 次第 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 vs 次第?
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.