Kotomora
JLPT N3Construction
Furigana

せいで・せいだBecause of; the fault of

せいで and せいだ blame a person, event, or circumstance for an unwanted result. The form carries a negative judgment, so it is not a neutral equivalent of “because.”

The result must be unwanted

The important feature is not simply cause and effect. By choosing せい, the speaker presents the cause as responsible for a problem, failure, inconvenience, disappointment, or other unwelcome result. The negative viewpoint should therefore be clear from the result or the surrounding context.

Blaming circumstances or yourself

The blamed cause may be outside the speaker’s control, or it may be the speaker’s own action.

隣となりの部屋へやがうるさかったせいで、ほとんど眠ねむれなかった。

Because the room next door was noisy, I could hardly sleep.

Analyze

The noise is blamed for the unwanted result.

私わたしが約やく束そくの時じ間かんに遅おくれたのは、目め覚ざましをセットし忘わすれたせいだ。

I was late because I forgot to set my alarm.

Analyze

Here the speaker accepts blame for their own mistake.

会かい議ぎが混こん乱らんしたのは、資し料りょうの数すう字じが間ま違ちがっていたせいだ。

The meeting became confused because the figures in the materials were wrong.

Analyze

The first part names the problem; the ending identifies what was responsible.

Blame, credit, or a neutral reason

せいで assigns blame for a bad result. おかげで does the opposite by giving credit for a favorable result. ので simply gives a reason without building blame or praise into the expression. Before choosing among them, decide whether the result is being judged as bad, judged as good, or merely explained.

More examples

渋じゅう滞たいのせいで、空くう港こうへの到とう着ちゃくが遅おくれた。

Arrival at the airport was delayed because of traffic.

Analyze

強つよい風かぜのせいで、電でん車しゃが一いち時じ間かんも止とまった。

Because of the strong wind, the train stopped for a whole hour.

Analyze

部屋へやが寒さむかったせいで、よく眠ねむれなかった。

It was too cold in the room to sleep well.

Analyze

説せつ明めいが曖あい昧まいなせいで、申もうし込こみ書しょを間ま違ちがえて書かいてしまった。

Because the explanation was unclear, the application form ended up being filled out incorrectly.

Analyze

隣となりで工こう事じをしているせいで、オンライン会かい議ぎに集しゅう中ちゅうできない。

The construction next door makes it impossible to concentrate on online meetings.

Analyze

私わたしが必ひつ要ような本ほんを買かえなかったのは、営えい業ぎょう時じ間かんを勘かん違ちがいしたせいだ。

I could not buy the book I needed because I had misunderstood the opening hours.

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パソコンが急きゅうに動うごかなくなった。停てい電でんのせいだ。

The computer suddenly stopped working. The power outage was to blame.

Analyze