〜なければならない

About

〜なければならない combines a negative ば (conditional) form verb, with ならない("won't become"). Together, they form a double negative (lit. "If not X, won't become") that describes things that "must" or "have to" be done.

〜なければならない is a very formal way to say "must/have to", and is mainly used in written Japanese. Its counterpart, 〜なければいけない, is used in both spoken and written language.

〜なければならない and other "must/have to" grammar that ends with ならない, tend to be used more for rules that apply to more than one person (e.g. laws for the general public), rather than personal matters.

As always, 〜なければならない can be made more polite by conjugating into the ます form (〜なければなりません).

Summary

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  〜なければならない is a formal way to say "must/have to".

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  〜なければならない tends to be used more for rules that apply to many people, rather than personal matters.

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  〜なければならない can be made more polite by conjugating into the ます form (〜なければなりません).