なぜなら

な

ぜ

な

ら

Common wordJLPTN3Freq.FrequencyTop 10,000

Meanings

1

conjunction

because; the reason is

usually written using kana alone

Used at the beginning of a sentence to introduce a reason or explanation, often followed by から or のだ.

画かく

に

反はん

対たい

です

。

なぜ

なら

、

費ひ

用よう

が

高たか

すぎる

から

です

。

I'm against the plan, because the cost is too high.

から
から is a more common and casual way to express 'because' and attaches to the end of a clause, while なぜなら is more formal and often used at the start of a sentence to emphasize the reason.
ので
ので also means 'because' but is slightly more formal than から and often used for objective reasons; なぜなら is more emphatic and typically used in written or formal speech.

Compound of なぜ (why) and なら (if it is). The exact historical derivation is uncertain, but it functions as a fixed conjunction meaning 'because'.