How to say 'must' in Japanese - なければならない, なくてはならない, だめだ

Author Anna Baffa Volpe for article 'How to say 'must' in Japanese - なければならない, なくてはならない, だめだ'

Anna Baffa Volpe

Today we see together 3 Japanese verbal structures with their variants that express duties and prohibitions, and they are:

  • なければならない
  • なくてはならない
  • だめだ

These expressions are very common to express things opportune and inopportune, what is more appropriate and socially accepted and what is best avoided.

なければならない - Duty, necessity

One of the commonly used forms that translate the verb must is なければならない or なければいけない.

  • なければ is the conditional form of ない (negative plain form of ある to be) if not there
  • ならない is the negative plain form of なる to become, if it's not there, it doesn't become, which translates as must be

How なければならない is formed

The negative plain form is used: in the suffix ない the vowel い is omitted and ければならない is added.

  • Verb: ()く, to go
  • Adjective in い, (さむ)い, cold
  • Noun: ()(そく), rule
  • Adjective in な: (しず)かな, silent: the particle な is omitted and the adjective behaves like a noun

なければならない - Needs and obligations

This form generally expresses necessities or duties relating to actions or things both of the person speaking and also when referring to other people.

The two keywords in this context are ()() obligation, duty, and (ひつ)(よう), need.

When to use ならない and when いけない

As you have noticed, we have two final verbs: ならない and いけない which we will also find in other forms. The distinction we are describe here below also applies to the other cases:

  • ならない is the negative form of なる to become and is used in social, community contexts, the things that are deemed appropriate or not socially

It is also used when discussing laws and regulations. ならない is more formal than いけない.

(しゃ)(かい)(じょう)(しき): "is common sense"


In Japan, when you enter a Japanese house, you must remove your shoes.

  • いけない is used for personal matters and is often found in ordinary and informal conversation

()(じん)(てき)なこと things, personal matters


Tomorrow I have to wake up at 6.

いけない is also used individually to express judgment, condemnation of someone or something, displeasure or even dislike. Different nuances depending on the situation.


It's not good, I overslept.


It seems he's sick, I'm so sorry.

Abbreviations and colloquial variants

The form in informal contexts is found in a number of ways:

  • simply なければ omitting the rest
  • なきゃ instead of なければ
  • なくちゃ instead of なければ


I need to return the money to my friend.


I have to study a lot.

なければいけない in an informal and colloquial context: audio and explanations




I wrote a letter to give Akari.


I really had a lot of things I needed to tell Akari and things I wanted her to hear.

(つた)えなければいけないこと: the verb used is (つた)える which means: convey, report, transmit or communicate なければいけない the form used in the sentence is translated as to need. The protagonist expresses the need to communicate somethings to Akari. Here we find another interesting structure that uses the て form of the verb combined with the adjective ()しい that means desiring, wishing for. ​ This is used to express the speaker’s desire for someone to do something (for him, her, them etc).


I want you to listen. to me.


I have a picture I want you to see.

なくてはならない - Prohibitions

なくてはならない and なくてはいけない express a prohibition, they are used in the context of regulations and laws.

なくてはならない and なくてはいけない can also be used to express situations of necessity, for essential things that cannot be done without.

How なくてはならない is formed

In this structure we simply find the te form of the verb combined with はならない or はいけない.


Questions not to ask in an interview.


Things prohibited in Japan.

(きん)() is the word that indicates the prohibition, not allowed

  • タバコの(きん)(えん) no smoking
  • (たち)(いり)(きん)() do not enter


We must respect the speed limit.

Example with the adjective (きん)(べん)diligent, hardworking, assiduous:


You students must be diligent.


You must do as I say.

Note in the two sentences the use of kimi which indicates the second person you and is used between friends and by people who are in a superior social position compared to the interlocutor.

なくてはならない - Indispensable


A person you can't live without.

  • the phrase means a person who, if he didn't exist, I couldn't live.
  • this type of sentence refers to someone indispensable: ()()(けつ)indispensable, essential

Other examples expressing prohibition


Using cell phones is prohibited in the library.

だめ - It's not good, it's not to be done

だめだ! or simply だめ! can be heard in the everyday life between parents and young children in Japan, it is an exclamation that expresses a prohibition, a very common reproach.

It is a strong, imperative expression that we translate:

  • no!
  • that's no good!
  • do not do it!

It is also used to express a prohibition in the form of advice in some situations.


You must not drink alcohol for a while.

As you can see there is always the forma in te + the adjective ()()な which singularly means useless, vain, unusable.

Differences between てはいけない and だめだ

  • -てはいけない is used in general situations
  • -てはだめだ instead for personal matters involving the speaker and the interlocutor

The forms of prohibition aimed at the person concerned are very strong and are generally pronounced by persons with authority: a policeman, a caretaker, a parent towards the children, a teacher towards the students, etc.

Below an example of a reproach of a parent to the child:


Don't cry!

ては becomes ちゃ on an informal, confidential level

We learned the forms なければならないなくてはならない with the final variants in いけない and also the use of だめだ. There are other ways to express prohibitions and prohibitions that we will learn in the next articles.


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