〜とたんに (totan ni)

JLPT N3

How to say something happened the very instant something else did.

Meaning

“The moment ~ / as soon as ~.” Right after the first action, a second (often surprising) one happened.

Formation

• Verb (た-form) + とたん(に)

Examples

ベッドに入ったとたん、眠ってしまった。

Beddo ni haitta totan, nemutte shimatta. — The moment I got into bed, I fell asleep.

窓を開けたとたんに、強い風が入ってきた。

Mado o aketa totan ni, tsuyoi kaze ga haitte kita. — The moment I opened the window, a strong wind blew in.

名前を呼ばれたとたん、彼は立ち上がった。

Namae o yobareta totan, kare wa tachiagatta. — The instant his name was called, he stood up.

家を出たとたんに、雨が降り始めた。

Ie o deta totan ni, ame ga furihajimeta. — The moment I left the house, it started to rain.

How it works

とたんに uses the past た-form and describes a sudden, often unexpected result that follows immediately. The second event is usually beyond the speaker's control.

Compared with similar expressions

• 〜とたんに — the moment ~ (sudden, unexpected result).

• 〜たら — when / after (result can be planned).

• 〜と — whenever (repeated / automatic).

Common mistakes

• Use the past た-form: 開けた → 開けたとたん (not 開けるとたん)

• The second clause is usually uncontrolled — not a command or intention.

Related grammar

• 〜たら — when

• 〜と — whenever

• 〜か〜ないかのうちに — as soon as (literary)