せい

せい
noun
fault, cause, blame
abstract
1. fault, cause, blame
The reason or cause of something negative. Used to attribute blame or responsibility for an undesirable outcome.
雨(あめ)のせいだ。
It's because of the rain.
寝不足(ねぶそく)のせいで頭(あたま)が痛(いた)い。
I have a headache because of lack of sleep.
全部(ぜんぶ)自分(じぶん)のせいにしないで。
Don't blame it all on yourself.
年(とし)のせいか、最近(さいきん)疲(つか)れやすくなった。
Maybe because of my age, I've been getting tired easily lately.

せい is used to attribute the cause of something negative. The kanji form 所為(せい) exists but is rarely used; hiragana is standard.

Common patterns

  • Noun + のせい: because of (noun)
  • Verb (plain form) + せいで: because (verb)
  • ～のせいにする: to blame on
  • ～のせいか: perhaps because of

Similar words

  • おかげ: thanks to (positive cause); せい is for negative causes
  • ～ため: because of (neutral, can be positive or negative)

Related Words

Compare: おかげ (positive cause)
general
Added 2026.2.8 6:20 · Revised 2026.10.10 3:51
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