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.




    You must do your studies every day.


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


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


    I must get off the train in Kyoto.


    You have to decide.

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なくてはならない – Grammar Discussion

Most Recent Replies (29 in total)

  • rexd


    The hint was " A very formal, usually written way to say that something must be done." I put in ~なければならない, but it wanted ~なくてはならない. Could anyone help me recognise when Bunpro is asking for なければ vs なくて?

  • joezcool02


    Same question here, I basically just try いけ always and change it to なら is it’s marked wrong. I can’t see the logic here, especially as the grammar note says it’s for more formal cases but these are listed as “standard”

  • stefyglp


    I saw the same hint “Negative non-past, Polite” and used the なくてはいけないです and got marked incorrect. The fact that Bunpro has all of these “must do/have to do” synonyms on the study site and then don’t specify which form they are asking for in the reviews is the most annoying thing I have encountered so far on this site.

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