Meaning
とたん(に) indicates that an action or event happens immediately after another action is completed or is about to be completed. It emphasizes the sudden, often unexpected occurrence of the second action right at the moment the first action finishes. The pattern uses the past tense form of a verb and is typically used to describe unforeseen consequences rather than intentional actions.
Formation
| Part of speech | Formation |
|---|---|
| 動詞（た形） | とたん（に） |
Examples
-
母からの手紙を見たとたん、彼女は泣き出してしまった。
The moment she saw the letter from her mother, she burst into tears. -
彼は電車を降りたとたん、走り出した。
The instant he got off the train, he started running. -
授業終了のベルが鳴ったとたんに、教室が騒がしくなりました。
The moment the end-of-class bell rang, the classroom became noisy. -
家のドアを開けたとたん、犬が大声で吠え出した。
The moment he opened the front door, the dog started barking loudly.
Summary
- Formation: verb in past tense (た) + とたん(に); always describes something unexpected happening at the moment another action finishes
- The action following とたん(に) must be in past tense and cannot express commands, intentions, assumptions, or negations
- Cannot be used to describe the speaker's own intentional actions; typically describes unforeseen consequences or reactions of others