Grammar › N4 · 06 Reasons, purposes & contrast

〜のだ: explanatory (it's that …)

N4 · 06 Reasons, purposes & contrast

Explains a reason or background; casual んだ, polite んです.

Plain form + のだ/んだ/んです (noun/na-adj: なんだ). Asks or gives reasons and excuses. Avoid for plain statements of fact.

Examples

どうして遅おくれたんですか。

Why were you late?

頭あたまが痛いたいんです。

My head hurts (that's the reason).