Grammar Point
expressions (phrases, clauses, etc.)
exp 
なければならない

have to do, must, should, ought to

Verb Negative stem + なければならない

This grammar point expresses a strong obligation or necessity, indicating that a certain action must be performed or a certain state must exist. It literally translates to 'if you do not do [action], it will not do'.

Verbs

For verbs, change the verb to its negative form, drop the final い, and add ければならない.

I must go home.

I have to buy a book.

Note

In formal writing or formal speech, なければなりません is used. This form implies a strong objective or social obligation, stating what is expected as a matter of course.

Adjective / Noun + なければならない

When used with adjectives or nouns, this indicates that a certain state or quality is absolutely necessary or required.

い-Adjectives

Drop the final い from the い-adjective and add ければならない.

It must be cheap.

な-Adjectives

Add でなければならない to the stem of the な-adjective.

It must be quiet.

Nouns

Add でなければならない directly after the noun.

It must be a student.

Note

For nouns and な-adjectives, the particle で is used before the conditional negative form. This construction is less common than the verb form but is used when a specific condition is required.

Variations and Casual Shortenings

In daily conversation, the conditional ending is frequently clipped or altered for speed and ease of pronunciation.

〜なければいけない and 〜なくてはいけない

The final verb ならない can be replaced with いけない. While ならない often implies a more objective or social obligation, いけない tends to imply a more personal or subjective obligation.

I have to take medicine.

I must hurry.

〜なきゃ

In casual speech, なければ heavily contracts into なきゃ. The ending ならない or いけない is often completely dropped.

I gotta wake up early tomorrow.

〜なくちゃ

Another common conditional negative is なくては, which shortens to なくちゃ in casual speech. Like なきゃ, the final verb is usually dropped.

I gotta study more.

Note

When using casual shortenings like なきゃ or なくちゃ, the final verbs are almost always omitted among friends. However, they can be added back for a slightly more polite but still colloquial tone, such as なきゃいけない.

Words: 
なければならない
なければなりません
なければいけない
なければいけません
ねばならぬ
ねばならない
ねばなりません
なければならぬ
なけばならない
Radicals of radicals