Like the title says, I'd like to know the difference in nuance and usage between 「することはない」 and 「しなくてもいい」。

For example:

「謝らなくてもいいよ」 vs. 「謝ることはないよ」

To me, they both sound like "You don't have to apologize [for that]." On one hand, 「…なくてもいい」 sounds slightly more conversational, but I think I've heard 「…ことはない」 in conversation too.

Also, in this answer, it says that 「…ことはない」 might have the nuance of something you don't have to do and probably shouldn't do. So maybe 「…なくてもいい」 means that you don't have to do it, but it's fine if you do.

Can anyone provide some insights into differences between these two grammar points?

  • 1
    Since that difference is subtle, it depends on who use, when he/she use, and in which context he/she use the word. Would you like to specify situations where those words are used?
    – cocoatomo
    Dec 3, 2014 at 13:26

1 Answer 1


There's a nuance, but most people will probably not give it a second thought.


  • Don't worry about it.
  • No need to say sorry.

There could be a valid reason to apologize, but it's not a big deal.

  • 娘{むすめ}: ママの大切{たいせつ}なお皿{さら}を割{わ}ってしまったよ!ごめんなさい。
  • 母{はは}: 謝{あやま}らなくていいよ。わざとやったわけじゃないから。


  • There's literally nothing to be sorry for.

  • ママ: 今日{きょう}パパのビールを買{か}ってくるのを忘{わす}れたわ。謝らなくちゃ。

  • 娘{むすめ}: 謝{あやま}ること(は)ないよ。いつも買{か}ってきてあげているじゃない?
  • 1
    Nice answer. One thing is that, 謝らなくていい doesn't imply that there is some reason to apologize, but just dispenses with mentioning it and focuses on necessity. Dec 3, 2014 at 16:26
  • I don't disagree, but 謝らなくていい may or may not imply there is some reason. And just for the record, 謝ることはない implies there is no reason at all.
    – j--
    Dec 3, 2014 at 16:43
  • I think I'm with you. It's that, I took your "a reason to apologize" as "a reasonable ground the speaker thinks to make one apologize". Dec 3, 2014 at 16:58
  • You are right. I changed it to "there could be a reason to apologize".
    – j--
    Dec 4, 2014 at 3:05

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