What's going on in this sentence?

I have the sentence “お客様に対しては, 礼儀正しくしねばなりません”, which I know means roughly “You have to be polite to customers”. However, I don’t understand the “しねばなりません”; is it a variant of the “なければなりません” grammar point? Can someone break it down for me?

What is the source of this sentence?

Anyways, I think you’re looking at this bit of N1 grammar.

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I’m curious too because it looks wrong to me. I think it should be せ, not し.

  • しない → しなければ
  • せぬ → せねば

Looks like this sentence incorrectly merges the two.

Some sources list it as N2, but regardless of the JLPT level ぬ and its conditional form ねば are pretty common if you read fantasy or older texts. Just figured I’d mention that since some people might misinterpret N1 as “don’t bother learning it”.


Are you sure it’s saying not saying to not politely die


しねばなりません is like “must” or “ought to” do something.

Similar to しなければならい

Except it should be せねば since it’s formed from the -ぬ rather than -ない form, which with する is せぬ

It’s true that [neg. verb stem] + ねばならない is a “must do” construction, but しねば would be, erm, 死ねば (Update: Just realized since the negative of 死ぬ is 死なない, then it would be 死なねば. 死ねば is just the regular conditional, so that would be a different grammar point. “Must not die” rather than “must do.” So it’s even more not what the sentence is supposed to be saying.)

せねば would make it causative (I think), which I don’t think makes sense in this scenario. You wouldn’t let people be polite to customers, you need to be polite to customers.

EDIT: I’ve done this grammar point in Renshuu and its verb + ねばならない, just to clarify ねば isn’t conjugating the same way like your example suggests.

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It’s the negative stem + (not just “verb” +), but する has multiple: し(ない) and せ(ぬ). Since ね is the conjugation of ぬ, not ない, it has to be せねば.


This says it’s from the -ない form, but as you can see from the two exceptions listed, it’s actually the -ぬ form, which with most verbs the stem is identical. But with ある it’s ない vs あらぬ, and with する it’s しない vs せぬ. Thus, せぬ⇒せねば + ならない/なりません


Alright, I’ll add that to my ねばならない knowledge. lol

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