Grammar Info

N5 Lesson 9: 7/13

~てはいけないMust not, May not

Structure

Verb[て]+ は + いけない

Details

  • Part of Speech

    Verb

  • Word Type

    Auxiliary Verb

  • Register

    Formal

About てはいけない

てはいけない is used in Japanese to express that (A) 'cannot', or 'must not' be done. It is the combination of a verb in form, the particle, and the negative potential form of () (to be able to go). In this way, it literally means '(A) cannot/is not able to go'.

Although can be dropped from many phrases and expressions, the in this particular grammar point is usually not. This is because いけない would then become the second action in a sequence of events (the usual function of form). However, to make this more casual, is often changed to ちゃ (ては becomes ちゃ), or じゃ (では becomes じゃ), as this is easier to say.

Caution

Apart from いけない; ならない and だめ are also frequently used to get across the same meaning. However, they are used in different situations.

いけない - Fairly neutral. Used in both spoken and written language.

ならない - Fairly formal. Used mostly in written language.

だめ - Very casual. Used almost exclusively in spoken language.

Antonyms


Examples

--:--

    そこ(はい)ってはいけない

    You must not go in there.

    クジラ()べてはいけない

    We must not eat whale.

    このビル(はい)ってはいけない

    You must not go into this building.

    (ばん)ごはん(まえ)、お菓子(かし)()べてはいけない

    You must not eat candy before dinner.

    この(いけ)(およ)いではいけません

    You must not swim in this pond.

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てはいけない – Grammar Discussion

Most Recent Replies (21 in total)

  • Jake

    Jake

    must not・may not

    Structure

    • Verb[] + は・いけない

    meaning
    must not・may not

    View on Bunpro

  • Lilalas

    Lilalas

    This is another grammar point where you should probably also mention the 漢字 spelling:

    ては行けない

  • mrnoone

    mrnoone

    Generally, when the verb is used as auxiliary etc, it is written using kana alone. That way it is distinguished from using it as a standalone verb.

    That’s why てはいけない、ておく(て置く)、てみる(て見る) are all written in kana. Using kanji may confuse readers.

  • CrisH

    CrisH

    This says to use long form て, but in 車で いってはいけない, いって is the shortest て form the verb has, isn’t it? Am I missing something? I thought the long form was 行かなくて, as when you’re saying you must do something.

    Thanks,
    Cris

  • Pushindawood

    Pushindawood

    @CrisH Hey! I think that the confusion may have come from the wording of the hint, with “て + いく” immediately following “long form.” The long form refers to the whole combination of て + は + いけない as opposed to shortened phrases like いっちゃだめ, or いったアカン (Kansai dialect). Cheers!

  • CrisH

    CrisH

    Ah, that’s probably it. I haven’t come across that yet, so I assumed long form was 行かなくて and short form was 行って. Thanks for clarifying

  • Pushindawood

    Pushindawood

    @CrisH 行かなくて and 行かないで are the negative て-forms of the verb 行く, while 行って is the plain て-form. 行かなくてはいけない means “(you) must go,” while 行ってはいけない means “(you) must not go.” Cheers!

  • deltacat3

    deltacat3

    Does anyone know why は is used in this construction and how it interacts with a verbs て-form? I am just curious is all.

  • testing

    testing

    What’s up with the sudden “いけません” in the “この池で泳いではいけません 。” example? It’s not mentioned in the Meaning section.

  • mrnoone

    mrnoone

    Hey and long time no see

    てはいけません is a polite form of てはいけない. It is made just like the ordinary polite negative form of a verb.
    で comes from the fact that the てform of 泳ぐ is 泳いで (it is still called a て form even though technically for those verbs its で).

    So:
    泳いで - て form of verb 泳ぐ
    泳いでいけない - short form
    泳いでいけません - polite form

    I hope it helps,
    Cheers


    Ask if you have any questions, I have caught a small cold so I might not explain clearly

  • Chewt

    Chewt

    If anyone was wondering where in [DBJG] this grammar is, its on page 528.

  • lasyat

    lasyat

    Why does the hint say て+いくinstead of て+いける? This confused me a bit.

  • Pushindawood

    Pushindawood

    @lasyat Hey! The hints are just there to steer you clear of using something like てはならない. If we provide too much of the actual grammar point (the partial conjugation in this case) then it becomes too easy to answer. The hint is just meant to get you in the right mindset (okay, this question is asking me to conjugate to the long form of て (as opposed to なくちゃ or なきゃ) first and then not use ならない). Cheers!

  • hachimagu

    hachimagu

    Hi,

    I would suggest to include “は + いけません” in the meaning box as well.

  • Kai

    Kai

    Not that it really matters, but it looks like there’s a rogue space in the title of this topic

  • mrnoone

    mrnoone

    @Kai @hachimagu

    Included

  • GrimeyPlopFlop

    GrimeyPlopFlop

    If this conjugation uses the verb 行く, why does the polite negative and non-polite negative conjugate as いけない and いけません instead of いかない and いきません like 行く does normally?

  • ResFort

    ResFort

    This construction uses the potential form of 行く (行ける, “can go”), not the dictionary form.
    So when conjugating it into the negative we get いけない/いけません (行ける itself is an ichidan verb).

    The literal translation for Aてはいけない is then something like “doing A cannot go”, which is better interpreted as “must not do A”.

  • GrimeyPlopFlop

    GrimeyPlopFlop

    Ah, that makes a a lot of sense, thank you!

  • notasas

    notasas

    The bunpro description states this contains “negative potential form of 行く”, however I’ve just encountered this:

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