What it means
せいで expresses a cause that leads to an unfavorable, troublesome, or regrettable result. It often suggests blame or criticism toward the cause and is commonly translated as “because of” or “due to.” It follows a noun with の, a na-adjective with な, and an i-adjective or plain-form verb directly. The form itself does not change for politeness; politeness is shown by the ending of the main clause.
Usage note
せいで normally has a negative or blaming nuance, so it is not the usual choice for a neutral or favorable result. For a favorable cause, おかげで is generally more appropriate, while ために can express a more neutral or formal cause.
How to use it
雨のせいで、試合が中止になりました。
Because of the rain, the match was canceled.
道が複雑なせいで、目的地に着けませんでした。
Because the route was complicated, I could not reach the destination.
寒いせいで、庭の花が枯れました。
Because it was cold, the flowers in the garden withered.
彼が連絡を忘れたせいで、計画が遅れました。
Because he forgot to make contact, the plan was delayed.
雨のせいで、試合が中止になった。
Because of the rain, the match was canceled.
道が複雑なせいで、目的地に着けなかった。
Because the route was complicated, I could not reach the destination.
寒いせいで、庭の花が枯れた。
Because it was cold, the flowers in the garden withered.
彼が連絡を忘れたせいで、計画が遅れた。
Because he forgot to make contact, the plan was delayed.
Example sentences
工事のせいで、駅までの道がいつもより混んでいます。
Because of the construction, the road to the station is more crowded than usual.
寝坊したせいで、朝の会議に遅れてしまいました。
Because I overslept, I ended up being late for the morning meeting.
強い風のせいで、ベランダの植木鉢が倒れてしまいました。
Because of the strong wind, the potted plant on the balcony fell over.
停電