1. Basic structure
| Type | Structure | Example pattern | Notes |
|---|
| Temporal clause | V-た + とたん(に) | 窓を開けたとたん(に)、風が入ってきた。 | Expresses "as soon as/just when ..."; emphasizes suddenness |
| Nominalization | その + とたん(に) | そのとたんに、停電になった。 | Used to mean "right at that moment" (refers back to the moment that just occurred) |
| Restrictions | Not used with volition/commands | × ドアを開けたとたん、入ってください。 | The following clause is usually something unexpected that happens instantly |
2. Main meaning & detailed analysis
- Expresses that something happens immediately right after the action in the first clause finishes.
- The second clause is often an unexpected result, beyond one's intention/control, and momentary.
- Commonly used with the past to recount events that happened; rarely used for predicted future.
- The subjects of the two clauses can differ, but the second clause should not express volition, commands, or invitations.
- Unlike ～たら/～とすぐ: ～とたん emphasizes the unexpected, sudden, instantaneous moment.
3. Example sentences
- ドアを開けたとたん、猫が飛び出した。
As soon as I opened the door, the cat leaped out. - 席に座ったとたん、電話が鳴り出した。
As soon as I sat down, the phone started ringing. - 彼の顔を見たとたん、涙があふれた。
The moment I saw his face, tears welled up. - 家を出たとたん、強い雨が降り出した。
As soon as I left the house, it began to pour. - 薬を飲んだとたん、眠気が襲ってきた。
The moment I took the medicine, drowsiness hit me. - スイッチを入れたとたん、電源が落ちた。
As soon as I flipped the switch, the power went out.
4. Usage & nuances
- Conveys a narrative feel of an unexpected event, happening in a flash.
- Not used to express the speaker's intention in the second clause (commands, advice, invitations, etc.).
- Often used with emphatic 副詞: そのとたん(に), ちょうどそのとたん(に).
- Frequently used with verbs of sudden change: 降り出す, 鳴る, 壊れる, 飛び出す, 立ち上がる, こみ上げる.
- Has a storytelling tone; suitable for writing and moderately formal speech.
5. Comparison, distinctions, and similar patterns
| Pattern | Meaning | Main difference(s) | Short example |
|---|
| V-た + とたん(に) | The moment; sudden | Focuses on the instant; second clause is often unexpected, beyond one's will | 外に出たとたん、雨。 |
| V-た + らすぐ(に) | Right after | General, not necessarily unexpected; allows volition/commands | 着いたらすぐ電話して。 |
| V-た + 瞬間 | The moment | Similar meaning, neutral style; does not emphasize "unexpected" as strongly | 会った瞬間、恋に落ちた。 |
| V-る/た + かと思うと/かと思ったら | No sooner ... than; just when ... | Conveys an observation of a quick change; subjects are often different | 泣いたかと思うと笑う。 |
| V-る/た + や否や | No sooner ... than (written style) | Formal, stiff style; not used with volition | 到着するや否や、会議。 |
6. Additional notes
- "とたん" can be written in kana: とたんに. The form "そのとたん" refers to the exact moment just mentioned.
- Expressing unexpected feelings is less common: the second clause is usually an objective occurrence.
- In narratives, "とたん" helps increase the tempo and create an unexpected climax.
- Related structures: "～や/～や否や" is mostly for written style; "～か～ないかのうちに" emphasizes an extremely short span.
7. Variations & fixed phrases
- V-た + とたんに
- そのとたん(に) + Clause
- ちょうどそのとたん(に) + Clause
- 見たとたん／聞いたとたん／触ったとたん… (perception verb group)
8. Common mistakes & JLPT pitfalls
- Using volition/command in the second clause: × ドアを開けたとたん、入ろう。→ Better: 開けたら入ろう。
- Using it for a prolonged action: × 仕事を始めたとたん、三時間働いた。→ Inappropriate because it's not sudden.
- Using present/predicted future: × 行くとたん、雨が降るだろう。→ Sounds natural when recounting the past.
- Confusing it with ～たらすぐ: ～とたん requires an element of surprise; ～たらすぐ is neutral and allows commands.
- It's fine if the subject is the speaker when it expresses a sudden sensation: 立ち上がったとたん、めまいがした (not a trap).
Time / Sequence / Process
