This means you must do something. It shows a strong need to act. It is a polite way to say it.
Verb [ない-form] + ければなりませんPrimary
This means you must do something. It shows a strong need to act. It is a polite way to say it.
ビザを更新するために、市役所へ行かなければなりません。
In order to renew my visa, I must go to the city hall.
昨日は一日中、会議に出席しなければなりませんでした。
Yesterday, I had to attend meetings all day.
この薬は、食後に飲まなければなりませんから、忘れないでください。
Since this medicine must be taken after meals, please don't forget.
お客様に失礼がないように、言葉遣いに気をつけなければなりません。
To avoid being rude to customers, we must be careful with our use of language.
無理な時は、はっきりと「できません」と言わなければなりません。
When something is impossible, you must state clearly, 'I cannot do it'.
This is like saying "must do" or "have to do." It is very polite. It is more formal than 〜なくてはいけません. You use it when talking about rules. Or when you talk about what society expects.
Watch out: This grammar means "must do." It does not mean "must not do." To say "must not do," use 〜てはいけません. For example, don't say タバコを吸わなければなりません to mean "You must not smoke." That means "You must smoke." Say タバコを吸ってはいけません instead.
Use this when you want to say something is a very strong duty. It is like saying 'we absolutely must do this'. You will see it in speeches or company rules. It is too strong for talking every day.
More formal alternatives(1)
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