I looked these words and means surely. Usually I see きっと, but is usual to use さぞ?



It's ok use both?

  • Do you mean the kanji or the adverbial expression for さぞ?
    – virmaior
    Dec 31, 2014 at 5:46
  • After 16 years of schooling in Japan, I never knew there was a kanji for さぞ.
    – user4032
    Dec 31, 2014 at 7:45
  • I mean the adverbial expression :)
    – sumitani
    Dec 31, 2014 at 12:34

1 Answer 1


Both きっと and さぞ are adverbs of epistemic modality (which means they express a type of uncertainty), but they're different in a number of ways:

  1. Level of certainty. きっと is more certain than さぞ.

  2. Frequency. きっと is significantly more common than さぞ.

  3. Register. きっと is normal in conversation.

    I've been told by more than one native speaker that さぞ sounds rather old-fashioned.

  4. Pragmatic restrictions. This refers to which contexts a word is appropriate in.

    さぞ is used under a narrower set of circumstances than きっと. When the speaker uses さぞ, they're expressing sympathy with the hearer or the sentence subject. It's somewhat subjective in nature. If this requirement isn't met, using さぞ is inappropriate.

    きっと doesn't have this requirement, so it can be used more generally.

  5. Modal harmony. This refers to co-occurrence with other expressions of modality.

    The adverb さぞ is very likely to co-occur with だろう (or でしょう, etc.) as in your example.

    Although きっと also co-occurs with だろう, it appears without it more often than さぞ does, and the greater degree of certainty means it's also possible for きっと to harmonize with relatively certain expressions like にちがいない.

Although both adverbs are possible in your example, as you can see they're not quite the same. By the way, さぞ is usually written in kana.

For more information about modality from a linguistics perspective, I recommend Heiko Narrog's Modality in Japanese (2009). Modal adverbs such as きっと and さぞ are covered on pages 108-110.

  • 1
    さぞ is indeed old-fashioned. If one sees or hears it 10 times, at least 9 times will be in fiction (novels, dramas, etc.). This, however, does not mean that one should use きっと all the time in real life because, in certain situations, it could make you look like you are being judgemental without evidence.
    – user4032
    Dec 31, 2014 at 7:41
  • Also literature? I saw this word in a JPLT vocabulary list (I don't know the level).
    – sumitani
    Dec 31, 2014 at 12:41
  • 1
    @Sumitani Certainly.
    – user1478
    Jan 1, 2015 at 10:21
  • 2
    Nowadays, only classy ladies and gentlemen seem to be qualified to vocally use this word with sympathy, in my opinion. If a friend of mine says this, I'll take it as an irony. Jan 1, 2015 at 10:51

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