～際（に）

• Reading: さいに
• Romaji: sai ni
• Formation: Verb dictionary form / Verb た-form + 際（に）/ Noun + の + 際（に）
• Kanji breakdown: 際: occasion, edge, boundary — indicates a noteworthy point or moment

Meaning

Expresses 'on the occasion of' or 'when' something happens, with a formal or special nuance. Used for important, notable, or official situations.

This pattern marks a specific occasion or situation, carrying a more formal and weighty tone than とき. It implies that the event is noteworthy, planned, or significant. 際に is commonly found in instructions, announcements, formal requests, and written notices. The pre-nominal form 際の is used before nouns. While とき is neutral and usable for any situation, 際に suggests the speaker considers the occasion important enough to warrant formal language. It would sound unnatural for trivial everyday events.

Examples

1. お申し込みの際に、身分証明書をご持参ください。 When applying, please bring your identification.
2. 海外に行く際は、保険に入ることをお勧めします。 When going abroad, I recommend getting insurance.
3. 引っ越しの際に、不要な物を処分した。 When I moved, I disposed of unnecessary things.

Usage Guide

Context: written, formal speech, instructions, business

Tone: formal

Do Say

• ご利用の際は、利用規約をお読みください。
• 緊急の際には、このボタンを押してください。
• 出張の際に、取引先を訪問する予定だ。
• 入学の際に必要な書類を確認した。

Don't Say

• ご飯を食べる際に、テレビを見た。(Using 際に for a trivial daily action — it sounds overly formal for eating dinner) → ご飯を食べるとき、テレビを見た。
• 友達に会った際に、遊んだ。(Using 際に for a casual social event — とき is more natural for informal situations) → 友達に会ったとき、遊んだ。

Origin & History

From the noun 際 (sai/kiwa), meaning 'edge, boundary, occasion.' In classical Japanese, it referred to the boundary between two states, evolving into its modern meaning of a specific occasion or juncture.

Cultural Context

Generation: All ages

Social background: Universal