N4 grammar
〜なくてはいけない
nakutehaikenai
Must, from the rules
Formationない stem + なくては + いけない
This is the same obligation as なければならない with a slightly more spoken feel. It is the exact mirror of てはいけません, so keep the two apart: one says you must, the other says you must not. Conversation cuts it down to なくちゃ.
Examples
〜なくてはいけない is marked in each sentence. Tap any word for its dictionary entry.
必ずあなたは来なくてはいけません。
By all means, you must come.
出かける前に食べなくてはならない。
You have to eat before you go.
彼は家を手放さなくてはならなかった。
He had to part with his house.
7時30分だ。大急ぎで行かなくては。
It's 7:30 now. I must fly.
その慣習は守らなくてはならない。
That institution must be protected.