N3Grammar

せいで

Because of, Due to, Blame

Structure

Verb + せいで
［い］Adjective + せいで
［な］Adjective + な + せいで
Noun + の + せいで

Explanation

Although typically written in hiragana, せい is a noun whose meaning is clarified by its kanji, 所為(せい), which translates to 'doings' or 'actions'. せい is used to attribute a negative outcome to a specific cause, person, or situation. Consequently, it is often translated as 'on account of', 'due to', or 'it's the fault of'.

As せい functions as a noun, it can follow the plain/dictionary form of verbs and i-adjectives, or be connected to other nouns with の. The case marking particle で is frequently attached to せい to explicitly mark the cause, clarifying that the negative result (B) happened 'as a result of' or 'by means of' that cause.

ゆうべケーキを食(た)べすぎたせいでお腹(なか)が痛(いた)い。
My stomach hurts because I ate too much cake last night.
雨(あめ)が強(つよ)いせいで試合(しあい)が中止(ちゅうし)になった。
Because the rain is so heavy, the match was cancelled.
明日(あした)のテストが不安(ふあん)なせいで食欲(しょくよく)がない。
Because I'm anxious about tomorrow's test, I don't have an appetite.
駅前(えきまえ)の工事(こうじ)のせいでバスが遅(おく)れている。
The bus is running late due to the construction in front of the station.

Fun Fact

The kanji for せい, 所為(せい), directly translates to 'doings'. This has a similar blaming nuance to how 'doings' can be used in English to assign fault. For example, 'The shattered vase was the cat's doings', or 'So you admit the prank was your doings!'

このミスは彼(かれ)のせいだ！
This mistake is his doing!
弟(おとうと)のせいでゲームに負(ま)けたんだ。
It's all my little brother's fault that I lost the game.

Examples

工事(こうじ)の騒音(そうおん)のせいで、夜(よる)よく眠(ねむ)れなかった。

I couldn't sleep well last night because of the construction noise.

これは私(わたし)のせいです。申(もう)し訳(わけ)ありません。

This is my fault. I am truly sorry.

エアコンのせいで体(からだ)がだるい。

I feel sluggish because of the air conditioning.

寝坊(ねぼう)したせいで、電車(でんしゃ)に乗(の)り遅(おく)れてしまった。

I missed the train because I overslept.

頭(あたま)が痛(いた)いのは、きっと寝不足(ねぶそく)のせいでしょう。

You probably have a headache due to lack of sleep.

渋滞(じゅうたい)のせいで約束(やくそく)の時間(じかん)に遅(おく)れてしまった。

I was late for my appointment because of the traffic jam.

たった一(ひと)つのミスのせいで、全部(ぜんぶ)やり直(なお)しになった。

Because of one single mistake, I had to redo everything.

弟(おとうと)がうるさかったせいで、勉強(べんきょう)に集中(しゅうちゅう)できなかった。

I couldn't concentrate on my studies because my little brother was being loud.

こんなに眠(ねむ)いのは、この薬(くすり)のせいかもしれない。

I might be this sleepy because of this medicine.

彼(かれ)が頑固(がんこ)なせいで、なかなか話(はなし)が進(すす)まなかった。

The discussion didn't get anywhere because he's so stubborn.

あなたのせいで負(ま)けたじゃないか！

We lost because of you!

試合(しあい)に負(ま)けたのは、自分(じぶん)の練習(れんしゅう)不足(ぶそく)のせいだ。

Losing the match is due to my own lack of practice.