Grammar Info

N5 Lesson 9: 9/13


Must do, Have to do

Also used to express duty or necessity. Click here if you are curious about なくて conjugation


Verb[ない+ なくては + ならない
Verb[ない+ なくちゃ + ならない


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About なくてはならない

Much like てはならない, なくてはならない states that something 'must not' be done. However, this is where the similarities end. なくてはならない is an example of a double negative in Japanese, and actually has the meaning '(A) must be done', or 'must do (A)'.

While this grammar point is usually translated as 'must do', the literal translation is 'must not, not do (A)'. This double 'not' is where many learners have difficulties. ならない simply means 'cannot become', and comes from the negative form of なる.

To use this structure, simply create the negative form of a verb, and then convert ない to なく (the conjunctive form of an い-Adjective), followed by . After this, is added, and then finally ならない.

ならない is considered to be the most formal structure out of ならない, いけない, and だめ. It is regularly used in formal writing, or semi-formal/formal speech. いけない (the most common variation) and だめ (the most casual variation) are also acceptable in many situations.


The ては in なくては is often shortened to ちゃ, as this is easier to say. なくちゃ may then be followed by ならない. However, due to ならない being quite formal, なくちゃ (a casual structure) will not be used with ならない on a regular basis. It is more common to see なくちゃ paired with いけない, or だめ.

  • 今日(きょう)沢山(たくさん)(はし)ったからシャワー()なくちゃならない
    Because I ran a lot today, I must take a shower.
  • バーベキュー(にく)()()なくちゃいけない
    I gotta bring meat to the barbeque.
  • (ふゆ)なる(まえ)キャンプ()なくちゃだめ
    We gotta go camping before it becomes winter, right?

These casual structures are very similar to words like 'gotta' in English.


  • 毎日(まいにち)勉強(べんきょう)なくてはならない

    You must do your studies every day.

  • ()(はん)までに銀行(ぎんこう)()なくてはならない

    By 3:30, I have to go to the bank.

  • もう()()ですまだ弁当(べんとう)()べてないです()なくてはならない

    It's already two?! I haven't eaten my bento yet. I have to eat.

  • 京都(きょうと)電車(でんしゃ)()なくてはならない

    I must get off the train in Kyoto.

  • (きみ)()なくてはならない

    You have to decide.

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なくてはならない – Grammar Discussion

Most Recent Replies (26 in total)

  • IcyIceBear


    Because that review is only testing ならない. They’re synonyms tested as two separate points. いけない doesn’t work only because it wants ならない specifically. Real world application they’re mostly interchangable

  • Meatdog


    Man this is the second question of mine you have answered, you are on fire! haha thanks again!

  • tangerine



    I don’t know if my settings changed or if the site changed but all I got as a clue for this one was “Negative non-past, Standard”, which seems a lot less helpful than the “long form / casual / て+なる” I see earlier in this thread.

    Is there something about the prompt that makes なくてはならない clear without cycling through all of the other permutations of "must"s out there? There are no alts for this one.

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