I've recently encountered a simple sentence in a video that confused me grammatically. (see 2:08)


My assumptions:

待っていない = negative continuous form of 待つ

といけない = have to

I've rarely seen this combination used in context and I can't find any resources online that explain this usage.

My questions are:

  1. Why doesn't the speaker say 待たないといけない instead? As far as I understand, it would mean the same thing.
  2. In what situations would I use this combination ていない+といけない?
  3. Am I correct in assuming this と is not the conditional と? If so, does this also apply to the other forms? i.e. ○○ていなくちゃいけない、ていなきゃいけない、ていないとだめ etc.

I appreciate any comments and feedback!

  • Apologies for making a complete mess of editing this. Sep 26, 2023 at 10:59

4 Answers 4


といけない does not mean "have to" by itself. と is "then", and いけない is "no good", so the combined meaning of といけない is something like "then (it's going to be) bad".

  • この本を子供が読むといけない。
    If kids read this book, then it's going to be bad.
    → Kids shouldn't read this book.

You need to add another ない for it to mean "have to" (i.e., double negative):

  • 子供はこの本を読まないといけない。
    If kids don't read this book, it's going to be bad.
    → Kids have to read this book.


  • 待つといけない。
    If you wait, then it's not good.
    → You should not wait.
    → Let's not wait.
  • 待っているといけない。
    If you keep waiting then it's not good.
    → You should not keep waiting.
    → Let's stop waiting.
  • 待たないといけない。
    If you don't wait, then it's not good.
    → You have to wait.
  • 待っていないといけない。
    If you don't keep waiting, then it's not good.
    → You have to keep waiting.

To answer your questions:

  1. 待たないといけない is also perfectly fine in this context, but the -teiru form implies you'll need to wait patiently for a while.
  2. Whenever you want the meaning of "keep ~ing", as you can see in the examples above.
  3. This と is the conditional と described here.
  1. The difference between 待っている and 待つ is whether continuous or not, as you are aware of. The difference there is smaller than other cases such as 立っている and 立つ probably because an action to wait is always made continuously to some extent. In negative forms, the difference gets less identifiable and sometimes used interchangeably. However, by saying 待っていないといけない, you can still add some implications such as waiting in front and/or a tone of continuous attachment/awareness/attention.

  2. I cannot explain gramatically, but native speakers would semantically decompose the phrase as 待ってい + ないといけない rather than 待っていない + といけない, where ないといけない as a whole means have to. It might be a matter of choosing preceding action rather than a situation used.

  3. I am not sure I understand your question correctly, but なくちゃいけない, なきゃいけない, ないとだめ are all variations of ないといけない.

  • Can you give me examples of when I can use てい+といけない and when I cannot use it? I would think that this can't be used in all situations. I made up this sentence as an example, let me know if it's unnatural 会議の前に重要な書類を提出していないといけない
    – shade549
    Sep 26, 2023 at 21:14
  • Your case sounds natural to me. If you say ...提出していないといけない, I would assume that I have to submit the document well in advance and attend the meeting with a cool face. If you say ...提出しないといけない, I would assume that submission at the very last minute is acceptable.
    – Ryo
    Sep 28, 2023 at 0:11
  • There might be a situation where ていないといけない sounds unnatural, but I don't come up with any right now. I'll try to find, but I would say you do not have to be too concerned about it.
    – Ryo
    Sep 28, 2023 at 0:25
  • 1
    Not grammatical again, but your concern may arise from the effect/function of ...ている. Differences between 待っている and 待つ, 提出している and 提出する, etc. might be better explained as "state or action" than "continuous or not" (I myself realized it now). If ...ている is a state, ないといけない can follow any state meaning "have to be in the state of", can't it?
    – Ryo
    Sep 28, 2023 at 0:58

As a logical matter: while いけない is usually considered as just an expression (or rather part of an expression), it's really the negative (as one would expect from its construction) of いける. We get a sense that the negated meaning is "isn't good; doesn't go well with; doesn't suit the situation" (like 合わない, but stronger - strong enough that it can be used to imply a prohibition, or as seen here, a requirement).

Japanese has a strong tendency to treat double negatives logically, rather than using them for emphasis (as in some Romance languages; English is somewhere in the middle). If not-continuing to wait is impermissible, it follows that waiting is obligatory. It's said this way because simply using a positive verb form wouldn't be able to create that sense of obligation - there's no explicit "must" modal, so the sense has to be created by excluding alternatives.

The same thing happens with the collocation しかない (which can be separated to some extent). しか is a particle analogous to は, but it adds a meaning of "other than". However, it's also a strongly negative polarity item, so it's only found with verbs in a negative conjugation. Supposing それしか言わなかった: if things other than "that" were not said, it follows that "that" is the only thing that was said.

So if I'm thinking straight, something like 待つことしかない should be roughly equivalent to 待っていないといけない, too. (As naruto says, the と is conditional, so it gives a sense of hypothesis; whereas しかない expressions simply assert that there is no choice.)


It would be very surprising if a native speaker were to parse 待っていないといけない as 待ってい + ないといけない. Leaving aside the analysis of 待っていない, with a bracketing notation, the sentence is construed as [[待っていない] と] いけない]. といけない does not form a constituent, nor does ないといけない (unless this were a sentence on its own meaning 'it must exist').

と simply means 'if' here, introducing the 'protasis' of a condition, and except for the fact that it is a separate word, the conditional meaning is conveyed no differently from 待っていなければ.

In other words, there is no single constituent in the sentence conveying the sense of obligation, it simply arises from saying 'if [I/we] don't stay waiting [for him], it won't do' => '[I/we] have to wait [for him]'. This [circum-]locution is common enough in Japanese and Chinese and Korean, but Japanese does have a verb form to express this, namely べき, 待つべきです, '[I/we] have to wait [for him]'.

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