At a glance
～際に means "when" or "on the occasion of". It is a formal way to say とき, used mostly in notices, manuals, business speech and writing.
Verb (dictionary form / た-form) + 際に
Noun + の + 際に
書類を提出する際に、印鑑が必要です。 An official seal is required when submitting documents.
How to form it
| Attaches to | Form | Example | Meaning |
|---|---|---|---|
| Verb (dictionary form) | 使う + 際に | 使う際に | when using |
| Verb (た-form) | 来た + 際に | 来た際に | when (someone) came |
| Noun | 外出 + の + 際に | 外出の際に | when going out |
Register: formal. 際は and 際には are also very common, especially before a request or instruction.