modality N4 common casual

〜じゃないか — isn't it ~?

〜じゃないか・じゃないか

Meaning

isn't it ~? / ~, isn't it / well, ~! — a casual tag that pushes the listener toward agreement, or marks a realization

じゃないか is the spoken contraction of ではないか. It rarely asks a real question — usually it nudges: 'come on, it's X, right?' (seeking agreement), or registers surprise on noticing something ('oh, it's X!'). Tone carries the difference; with falling intonation it can also gently scold (だから言いったじゃないか — 'I told you, didn't I').

Key sentence

それでいいじゃないか。

That's fine, isn't it?

Formation

Attaches to	Form	Example
Plain form / noun / na-adjective (ではない → じゃない + か)	… plain + じゃないか	面白おもしろいじゃないか / 簡単かんたんじゃないか / 雨あめじゃないか

Examples

あれ、財布さいふがないじゃないか。

Hey, my wallet's gone!

やればできるじゃないか。

See, you can do it when you try, can't you.

もう時間じかんがないじゃないか。

We're out of time, aren't we.

Easily confused with

〜ではないか Same structure, different register: じゃないか is the everyday casual contraction; ではないか is its formal/written full form, used in speeches and writing. ねね softly invites shared agreement; じゃないか presses harder — it argues a point or flags a discovery, often with a note of surprise or insistence.

Notes

Politer spoken variants soften the push: じゃない (rising), じゃないですか. The か can also drop entirely, leaving じゃない as the casual tag.

See 〜じゃないか in real sentences

Jengo shows 〜じゃないか the way you actually meet it: inside real Japanese sentences, so it sticks instead of staying an abstract rule.

Study it in Jengo

← Back to the grammar tree