際にsai ni“when; at the time of”

際に（さいに） means when; at the time of. It is a JLPT N3 grammar pattern used to mark the time or occasion for an action, often in formal notices.

This grammar point often appears in formal Japanese. If you want to mark the time or occasion for an action, often in formal notices, 際に（さいに） is a useful pattern to learn.

What does 際に（さいに） mean?

Use 際に（さいに） when you want to mark the time or occasion for an action, often in formal notices.

Natural translations include:

• when; at the time of
• when
• when / at the time of

How to form 際に（さいに）

Nounの / Verb dictionary・た-form + 際に

Examples of the pattern:

• お帰りの際に
• 申し込む際に
• 利用する際に

When is 際に（さいに） used?

Use 際に（さいに） in situations like:

• formal instructions
• announcements
• procedures and occasions

Tone and register:

• formal
• Common in JLPT reading, grammar questions, and natural Japanese sentences

際に（さいに） example sentences

• お帰りの際に、受付に鍵を返してください。 — When you leave, please return the key to reception.
• 申し込む際に、身分証明書が必要です。 — When applying, identification is required.
• この機械を使う際には、説明書を読んでください。 — When using this machine, please read the manual.
• 来日した際に、京都を訪れました。 — When I came to Japan, I visited Kyoto.
• 災害の際には、落ち着いて行動してください。 — In the event of a disaster, please act calmly.

Nuance of 際に（さいに）

The key nuance is formal occasion marker, common in instructions.

This matters because 際に（さいに） does more than translate one English phrase. It shows how the speaker connects ideas, evaluates a situation, or frames the sentence for the listener.

For example:

• In context, it sounds natural when the surrounding sentence supports the nuance.
• Compared with 時に, it has a different focus and level of formality.

際に（さいに） vs 時に

Both 際に（さいに） and 時に can appear in related situations, but they are different.

際に（さいに）:

• means when; at the time of
• fits the specific N3 pattern and nuance explained above

時に:

• 時に is general “when”; 際に is more formal and procedure-like

Quick contrast examples:

• Target: お帰りの際に、受付に鍵を返してください。 — When you leave, please return the key to reception.
• Compare: Try replacing it with 時に and check whether the nuance still matches.

Common mistakes with 際に（さいに）

Watch out for these mistakes:

• Using it in casual conversation where 時 is more natural
• Forgetting の after nouns
• Using it for everyday repeated habits

Is 際に（さいに） on the JLPT?

Yes. 際に（さいに） is commonly taught as JLPT N3 grammar.

That means learners should be able to:

• recognize it in reading
• understand its nuance in context
• use it in simple original sentences

Practice questions for 際に（さいに）

• Write a notice about returning a key.
• Say ID is needed when applying.
• Describe what to do in a disaster.

Learning path for 際に（さいに）

To learn 際に（さいに） efficiently, review basic time connectors first, then focus on whether the action happens before, during, immediately after, or while something is still true.

1. First, make sure you can form 際に（さいに） without looking at the pattern chart.
2. Next, compare it with 上で（うえで）, たとたん.
3. Finally, write short narratives where timing changes the meaning; then check whether replacing 際に（さいに） with たて changes the meaning.

Related grammar to review next

• 上で（うえで） — after; when; for the purpose of.
• たとたん — as soon as; just when.
• たて — freshly; just done.
• うちに — while; before.

Learn 際に（さいに） with Hane

If you want to review 際に（さいに） together with the related patterns above, Hane helps you practice Japanese in short, focused sessions.

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