Meaning & Usage
✨ Basic Meaning
‘When’, ‘At the time of’, or ‘On the occasion of’.
🎯 Primary Function
To indicate a formal time or occasion when an action occurs.
📋 Grammar Structure
Verb (Dictionary form / Ta-form) + 際に / Noun + の + 際に
i-adjective + 際に (rare)
na-adjective + な + 際に (rare)
Verb (Nai-form) + 際に
🎭 Usage Contexts
Formal Situations
Very common in business, ceremonies, and official documents.
Informal Situations
Rarely used; ‘toki’ is preferred in daily conversation.
Written Language
Standard in business emails, manuals, and formal letters.
Spoken Language
Used in formal speeches, news reports, and announcements.
💡 Common Applications
Business Correspondence
Used in emails to refer to specific actions taken at a point in time.
Example: 資料を送付した際に (When I sent the documents)
Public Announcements
Used in train stations or airports for formal instructions to the public.
Example: 乗車する際に (When boarding)
Manuals and Guidelines
Used in written instructions to indicate the timing of a necessary action.
Example: 使用の際に (When using)
Frequency
High in formal/written Japanese.
Difficulty
JLPT N3 (Intermediate)
Tag:
Example Sentences
Example #1
入室する際に、靴を脱いでお入りください。
Furigana: にゅうしつするさいに、くつをぬいでおはいりください。
Romaji: Nyuushitsu suru sai ni, kutsu o nuide ohairi kudasai.
English: Please take off your shoes when entering the room.
Example #2
ビザを申請する際に、この書類が必要です。
Furigana: ビザをしんせいするさいに、このしょるいがひつようです。
Romaji: Biza o shinsei suru sai ni, kono shorui ga hitsuyou desu.
English: These documents are necessary when applying for a visa.
Example #3
非常の際には、エレベーターを使わないでください。
Furigana: ひじょうのさいには、エレベーターをつかわないでください。
Romaji: Hijou no sai ni wa, erebeetaa o tsukawanai de kudasai.
English: In case of an emergency, please do not use the elevator.
Example #4
この機械を利用する際には、説明書をよく読んでください。
Furigana: このきかいをりようするさいには、せつめいしょをよくよんでください。
Romaji: Kono kikai o riyou suru sai ni wa, setsumeisho o yoku yonde kudasai.
English: Please read the manual carefully when using this machine.
Example #5
社長とお会いした際に、名刺を交換しました。
Furigana: しゃちょうとおあいしたさいに、めいしをこうかんしました。
Romaji: Shachou to oai shita sai ni, meishi o koukan shimashita.
English: I exchanged business cards when I met the president.
Example #6
お振込みの際には、手数料がかかります。
Furigana: おふりこみのさいには、てすうりょうがかかります。
Romaji: Ofurikomi no sai ni wa, tesuuryou ga kakarimasu.
English: A fee will be charged at the time of bank transfer.
Example #7
予約の際に、お名前をお知らせください。
Furigana: よやくのさいに、おなまえをおしらせください。
Romaji: Yoyaku no sai ni, onamae o oshirase kudasai.
English: Please inform us of your name when making a reservation.
Example #8
ウェブサイトにログインする際に、エラーが発生しました。
Furigana: ウェブサイトにログインするさいに、エラーがはっせいしました。
Romaji: Webusaito ni roguin suru sai ni, eraa ga hassei shimashita.
English: An error occurred when logging into the website.
Example #9
お帰りの際は、お忘れ物のないように気をつけてください。
Furigana: おかえりのさいは、おわすれもののないようにおきをつけください。
Romaji: Okaeri no sai wa, owasuremono no nai you ni ki o tsukete kudasai.
English: Please be careful not to forget anything when leaving.
Example #10
次回お目にかかった際に、詳しくご説明いたします。
Furigana: じかいおめにかかったさいに、くわしくごせつめいいたします。
Romaji: Jikai ome ni kakatta sai ni, kuwashiku gosetsumei itashimasu.
English: I will explain the details when we meet next time.
Notes & Nuances
📌 Important Points
Emergency situations
It is often used in ‘In case of…’ scenarios.
Example: 非常の際に (In case of emergency)
Compatibility with Keigo
It frequently pairs with Keigo (honorific/humble) verbs.
Example: お帰りの際 (When returning home – polite)
Action-oriented timing
The ‘ni’ is often followed by a required action or condition.
Example: 申し込みの際に (When applying)
⚠️ Common Mistakes
❌ 朝食を食べた際に、コーヒーを飲んだ。 (Choushoku o tabeta sai ni…)
✅ 朝食を食べたとき、コーヒーを飲んだ。 (Choushoku o tabeta toki…)
‘Sai ni’ is too formal for trivial daily routines like eating breakfast.
🏛️ Cultural Context
Politeness Level: Formal (Teinei/Keigo context).
Social Situations: Essential for professional interaction and understanding public signage.
Regional Variations: Standard across Japan.
🔍 Subtle Differences
際に vs. とき (Toki)
‘Toki’ is used for any time (casual or formal). ‘Sai ni’ is strictly formal.
When to use: Use ‘Toki’ for daily life; use ‘Sai ni’ for business or public instructions.
際に vs. に際して (Ni saishite)
‘Ni saishite’ focuses on the preparation or start of a big event. ‘Sai ni’ is simply ‘when’.
When to use: Use ‘Ni saishite’ for ‘on the occasion of starting something’ like a wedding or new business.
📝 Conjugation Notes
‘Sai ni’ functions as a noun, so nouns require ‘no’ and verbs use the plain form (present or past). ‘Ni’ can sometimes be omitted as ‘Sai’ or replaced with ‘Sai wa’ for emphasis.
🔊 Pronunciation Tips
Pronounced as two distinct syllables ‘sa-i’. In ‘Sai wa’, ensure the ‘wa’ is clear to indicate the topic.
🧠 Memory Tips
Think of ‘Sai’ as the formal sibling of ‘Toki’. If you are writing an email to a boss or reading a warning sign, expect to see ‘Sai’.
Other Grammar
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