N2 Timing, Occasions, and Triggers

~際さいに(は): meaning, usage and examples

~際さいに(は) means: when... / at the time of...

Updated 9 November 2026 · By the My Senpai team · Spotted a mistake? Tell us

Examples

1. ご利用りようの際さいには、注意事項ちゅういじこうをお読よみください。

   Before use, please read the precautions.

2. 出発しゅっぱつの際さいに、確認かくにんしてください。

   Please confirm at the time of departure.

3. 書類しょるいを提出ていしゅつする際さいには、印鑑いんかんが必要ひつようです。

   When submitting the documents, you will need your personal seal.

4. お車くるまでご来店らいてんの際さいには、受付うけつけでお知しらせください。

   If you come by car, please let the front desk know.

When to use it

Use 際さいに as a more formal way to say 時とき (when, at the time of). It is the standard choice in notices, instructions, manuals and polite customer speech: 書類しょるいを提出ていしゅつする際さいには、印鑑いんかんが必要ひつようです (when submitting the documents, you need your seal). The は in 際さいには adds a sense of "in that particular case".

Nuance

Formal and polite; common in signs, announcements and service language, rare in casual talk. It suits specific occasions rather than repeated habits, and it does not sound natural with emotions or the weather as a general state (寒さむい際さいに is odd). In speech, polite forms like ご利用りようの際さい are typical.

Compare

時とき is the everyday word and fits any context: 暇ひまな時ときに読よむ. 際さいに is its formal version: お帰かえりの際さいは忘わすれ物ものにご注意ちゅういください. に際さいして is stiffer still and attaches straight to a noun for a significant event: 開会かいかいに際さいして挨拶あいさつする.

Tip: Picture a station announcement or a hotel notice. If the sentence could appear there, 際さいに fits; with friends, say 時とき.