JLPT N4 Elementary

なのだ

Sentence ender framing a statement as an explanation or reason.

Readings

Other forms

なんだ casual contraction

のです polite form

んです common polite contraction

Grammatical Phrase / Sentence Ender

Explaining a Reason or Context

Frames the statement as an explanation, rationale, or clarification regarding the current situation or implied context.

Good to know

なのだ adds an explanatory tone to a statement.

Use it when giving the reason, cause, or background behind a situation. It often feels like “the thing is…”, “it’s because…”, or “what’s going on is…”

It attaches after a noun or な-adjective with な, as in 雨（あめ）なのだ. With verbs and い-adjectives, use のだ instead.

Common forms:

• なのだ: basic form. Can sound assertive, literary, or a little stiff in daily speech. • なんだ: casual spoken form. • なのです / なんです: polite conversational forms.

In questions like なのですか or なんですか, the speaker is often asking for the reason or story behind the situation, not just a yes-or-no answer.

Be careful not to overuse なのだ. Because it strongly signals “I’m explaining why,” using it too often can sound defensive, argumentative, or like you are making excuses.

Example

すみません、電車が遅れたんです。

I'm sorry, the situation is that the train was late.

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VOCAB 2 / 30

なのだ

Sentence ender framing a statement as an explanation or reason.

Example

この言葉を覚えましょう。

Let's memorize this word.

Again

Hard

Good

Easy