ないといけない
must; have to
Use a negative verb followed by といけない to say that an action is necessary.
In plain language
ないといけない means “have to” or “must.” It says an action is necessary. Although it contains a negative form, the whole expression means you need to do the action.
When to use it
Use it for obligations such as going to school, eating before leaving, or returning a book today. ないといけません is the polite form.
How to build it
Start with the plain negative verb: 行く → 行かない. Add といけない or polite といけません: 行かないといけません (“have to go”).
A basic pattern
Verb ない-form + といけない
Examples in context
The grammar point is shown in blue in each sentence.
明日は学校に行かないといけません。あしたはがっこうにいかないといけません。I have to go to school tomorrow.
出かける前に朝ごはんを食べないといけない。でかけるまえにあさごはんをたべないといけない。I have to eat breakfast before going out.
今日はこの本を返さないといけません。きょうはこのほんをかえさないといけません。I have to return this book today.
Watch for this
食べませんといけません。 → 食べないといけません。
The verb before と stays in the plain ない-form. Put politeness in the final ending.
Quick practice: ないといけない
Check what you remember with three short questions. Your result stays in this browser.