modality N4 essential casualpolitewritten
なければいけない — must ~
なければいけない
Builds on なければ
Meaning
- must ~ / have to ~ — an obligation, framed as 'if I don't, it won't do'
Key sentence
明日までにこの書類を出さなければいけない。
I have to submit these documents by tomorrow.
Formation
| Attaches to | Form | Example |
|---|---|---|
| Verb (ない-form, drop い) | V-なけれ + ばいけない | 出す → 出さない → 出さなければいけない |
| Noun / na-adjective | N/na-adj + でなければいけない | 会員でなければいけない |
Variants
なきゃ（いけない） — casual contraction; the いけない is often dropped: 帰らなきゃ ('gotta go home').
Examples
薬は毎日飲まなければいけません。
You have to take the medicine every day.
もう帰らなければいけない。
I have to head home now.
答えは正確でなければいけない。
The answer has to be exact.
Easily confused with
〜なければならない Same 'must', same なければ base. いけない feels personal / this-situation; ならない states a general rule or social obligation and leans more formal. 〜なくてはいけない Identical meaning, different conditional base: なければ (slightly more formal/written) vs なくては (a touch more conversational). 〜なくてもいい Opposites: なければいけない = 'must do'; なくてもいい = 'don't have to'.
See なければいけない in real sentences
Jengo shows なければいけない the way you actually meet it: inside real Japanese sentences, so it sticks instead of staying an abstract rule.
Study it in JengoSources Compiled with reference to A Dictionary of Advanced Japanese Grammar.