なぜ

な

ぜ

Common wordJLPTN5Freq.FrequencyTop 500

Meanings

1

adverb

why; how; for what reason

usually written using kana alone

Standard question word asking for a reason or cause. Can be used in both formal and informal contexts.

なぜ遅おくれた

の

です

か

。

Why were you late?

なぜそう思おもうの？

Why do you think so?

Usage patterns

なぜ〈事こと〉のかwhy (something happened/is the case)
なぜ彼かれが来こなかったのか分わからない。
I don't know why he didn't come.
なぜだろうI wonder why
電でん車しゃが止とまっている。なぜだろう。
The train has stopped. I wonder why.
なぜ〈事こと〉のですかpolite way to ask why
なぜ会かい議ぎに遅おくれたのですか。
Why were you late for the meeting?

Grammar

なぜ・どうして＋かというと・かといえばIntroducing a reason with a why-frameN3

Kanji

何what
故happenstance, especially, intentionally

Related words

どうしてN5
どうして is more colloquial and can also mean 'how' in the sense of method, while なぜ is a straightforward, neutral 'why' asking for a reason.
何なんでN3
なんで is a casual spoken form of 'why', often used in informal conversation, whereas なぜ is neutral and fits both formal and informal settings.
何なに故ゆえN1
なぜ is the everyday neutral word for 'why', while 何故 is a formal, literary variant used in writing and speeches.

Don't confuse with

なぜかN2
なぜ is the question word 'why' used to ask for a reason, while なぜか adds か to mean 'for some reason' without asking anything.
なぜならば
何故 (なぜ) is the question word 'why', while なぜならば is a conjunction meaning 'because', not a question.

Word family

なぜかN2
somehow; for some reason; without knowing why
なぜならN3
because; the reason is
なぜに
why; how come
なぜだか
somehow; for some reason; without knowing why

Written forms

なぜUsage84%
gikun (meaning-based reading) or jukujikun
Kana spelling is standard; the kanji form 何故 is rare and literary.
何故なぜUsage15%
gikun (meaning-based reading) or jukujikun
Kanji form is occasionally seen in formal or literary writing but is not common in everyday use.
ナゼUsage<1%

Etymology

The word なぜ is a native Japanese interrogative. The kanji spelling 何故 is a jukujikun reading, where the characters are assigned based on meaning rather than sound.

なぜならば

because; the reason is