I would like to know which is the meaning of the structure ~ずにはすまない.

According to several pages that I've found on Google, it means "must, have to" as well as ~なければならない. However, in other websites ~ずにはすまない seems to mean "not having another option than" (like ~ざるを得ない). If ~ずにはすまない means the same as ~なければならない or ~ざるを得ない, I would like to know the difference between these structures.

If besides that, you could please give me an example of ~ずにはすまない I would be really thankful.

  • Here's a question on a closely related pattern, but with すむ in the positive rather than the negative so that means the opposite – it's OK not to do whatever. japanese.stackexchange.com/questions/23903/… Maybe that helps at least a little?
    – Nanigashi
    Commented Sep 23, 2020 at 22:37

1 Answer 1


As far as I understand, ~ず is a more formal alternative to ~ないで and すむ is "to live", so it will be something along the lines of "Can't live without ~ing", which would match both "have to" and "not having another option than". and my guess about すむ was completely off. See @Nanigashi 's comment below.

  • 1
    Surely this must be ~ずには済まない, as opposed to ~ずには住まない? (And if you actually did want to say "can't live without ~ing" in Japanese, wouldn't you use 生きる rather than 住む? Maybe something like "~ずには生きられない" or "~ずには生きていけない"?)
    – Nanigashi
    Commented Sep 23, 2020 at 19:00
  • @Nanigashi I admit I was guessing (about すむ). Might be a good idea to write this comment as an answer instead Commented Sep 23, 2020 at 19:10
  • Thanks, but I think it's better I leave this to someone else. I basically know what this pattern means, but I'm sure there are nuances that I don't fully grasp, like when and why one would choose this over other ways of saying someone "must" do something. In other words, I'm hoping someone much better qualified than I am will jump in!
    – Nanigashi
    Commented Sep 23, 2020 at 22:28
  • Doesn't seem like their are many takers )) Commented Sep 23, 2020 at 22:29
  • I'm surprised it hasn't been asked and answered already. I wasn't able to find a question on this exact pattern on the site, though there are some on related usages of 済む. For example, here's one on ~なくてもすむ, which means one doesn't have to do something: japanese.stackexchange.com/questions/23903/… But of course, that doesn't address the OP's question about the difference between ~ずにはすまない and other patterns like ~なければならない or ~ざるを得ない.
    – Nanigashi
    Commented Sep 23, 2020 at 22:35

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