How to tell them apart
際（に） marks a formal, special occasion and sounds stiff in everyday speech, while 時・とき is the general word for any time or moment. Use 際（に） for ceremonies, important opportunities, or set phrases like この際; use 時・とき for routine events like 食べる時 or 寝る時. Swapping them feels odd: 卒業の際に is natural, but 朝ごはんを食べる際に sounds overly formal.
- 際（に） Use 際（に） for formal or special occasions like graduations, ceremonies, or important opportunities.
- 時・とき Use 時・とき for ordinary, everyday timing without any special or formal nuance.
| Grammar point | Meaning | JLPT level |
|---|---|---|
| 際（に） ni | at the time of, on the occasion of (formal usage) | N3 |
| 時・とき toki | at the moment when; during the period of | N5 |
際（に） ni
at the time of, on the occasion of (formal usage)
際(に) means at the time of or on the occasion of, used to mark a specific moment or opportunity when something happens. It follows nouns with の, as in 面接の際に, and verbs in dictionary form for future events or た form for past events, as in 申し込む際に or 引っ越した際に. It is formal and common in announcements, instructions, and business writing, and に is often optional without much change in meaning.
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海外へ旅行する際には、通常、パスポートが必要である。
When you travel abroad, you usually need a passport.
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申し込む際に身分証が必要です。
You need ID when you apply.
時・とき toki
at the moment when; during the period of
とき means when or at the time, and points to the moment or period in which the main action happens. It follows a plain form clause such as 行くとき, 行ったとき, 忙しいとき or 静かなとき, with past or nonpast showing whether that time is before or after. After a noun it needs の, as in 高校のとき or 子供のとき, and attaching 時 directly to a noun sounds like a formal suffix. It is neutral and common in both speech and writing.
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バスで行く時もあれば車で行く時もある。
Sometimes I go by bus and sometimes by car.
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時間のあるときは何をしていますか。
What do you do in your free time?
際（に） and 時・とき are JLPT N5–N3 grammar points that Japanese learners often mix up. This page compares them side by side on meanings, usage and example sentences, so you can tell them apart.