Japanese grammar

What does ～さいちゅうに mean? Japanese grammar N3

～さいちゅうに means right in the middle of ~ing, something else happens.

Quick facts
Level (estimated, JLPT framework)	N3
Structure	Vている + 最中に Nの + 最中に
Romaji	saichuuni
Meaning	right in the middle of ~ing, something else happens

Forming it

Noun	会議 + の + 最中に
Verb	話している + 最中に

How to use it

Emphasizes that the event in the second clause happens RIGHT IN THE MIDDLE of an action in full swing, usually causing an interruption or inconvenience.

「～最中に」 emphasizes that the event in the second clause occurs right in the MIDDLE of an action at its peak/in progress. It's stronger than 「～ているときに」 in emphasizing "right in the middle of it".
The second clause is usually something that causes an interruption, inconvenience, or is unwanted.
Only used with an ongoing activity that HAS DURATION (a meeting, eating, talking), not with a momentary event.

Examples

会議(かいぎ)の最中(さいちゅう)に、携帯(けいたい)電話(でんわ)が鳴(な)ってしまった。
Right in the middle of the meeting, my phone rang.
発表(はっぴょう)をしている最中(さいちゅう)に、頭(あたま)が真(ま)っ白(しろ)になった。
Right in the middle of my presentation, my mind went blank.

Keep in mind

Nouns denoting an activity (会議, 食事) connect with 「最中に」 via 「の」.
「最中だ」 (without 「に」) ends the sentence, meaning "right in the middle of...".

Common mistakes

Wrong駅(えき)に着(つ)いた最中(さいちゅう)に、電車(でんしゃ)が出(で)た。

Just as I arrived at the station, the train left.

Correct駅(えき)に着(つ)いたとたんに、電車(でんしゃ)が出(で)た。

「最中に」 requires an action that is ONGOING; a momentary event like "just arrived" should use 「とたんに」.
Wrong食事(しょくじ)の最中(さいちゅう)に、おいしかった。

In the middle of the meal, it was delicious.

Correct食事(しょくじ)の最中(さいちゅう)に、地震(じしん)があった。

The clause after 「最中に」 is an event that OCCURS in the middle of something (an earthquake), not a static feeling.

Exam tips

「最中に」 requires an ongoing action; for a momentary event use 「とたんに」.