Grammar Info

N2 Lesson 5: 15/18


Suddenly, Unnoticed, Without noticing, Too soon


いつのまに + Phrase


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About いつの間にか

Although a combination of いつ 'when', の, () 'interval', に, and か; いつの()にか is a set expression that is used as a stand-alone adverb to mean 'suddenly', or 'without noticing'. Literally, it just highlights an unknown interval within which something occurred, as seen by the question marking particle, か.
  • 3年間(ねんかん)日本人(にほんじん)友達(ともだち)毎日(まいにち)日本語(にほんご)(はな)していたら、いつの()にか日本語(にほんご)上手(じょうず)になっていた。
    After three years of speaking Japanese every day with my Japanese friend, I became fluent in Japanese without noticing.
  • (ひさ)しぶりにクレジットカードの明細(めいさい)確認(かくにん)してみたら、いつの()にか自動車(じどうしゃ)保険(ほけん)値段(ねだん)()がっていた。
    I checked my credit card statement for the first time in a while and found that the price of my car insurance had suddenly gone up.
  • ()づいたら、いつの()にか(ふゆ)になっていた。
    Before I knew it, it was winter.
Fun-fact - Coming mainly from the inclusion か, this grammar pattern often carries the nuance of surprise. When you want to convey the same feeling without the nuance of surprise, あっという() may be used instead. This is a similar expression which literally means 'in the time it takes to say あっ'.
  • (たの)しいことをしているとあっという()時間(じかん)()ぎるよね。
    Time flies when you're having fun, doesn't it?


  • しばらく入院(にゅういん)して(ひさ)しぶり(そと)()と、いつ()にか(ふゆ)になっていた(こと)()づいた。

    After being hospitalized for a while, I went outside for the first time in ages and noticed that it had become winter without realizing it.

  • いつ()にか彼女(かのじょ)はネイティブみたいに(はな)せるようになった。」

    'Without me realizing, her speaking has grown to that of a native.'

    Since いつのまにか is not used when a change is gradual, the sentence suggests that the speaker has not seen her for a long time, and during that time she has become proficient with language.

  • あなた子供(こども)から()(はな)せばいつのまにか迷子(まいご)になるかもしれない。ご注意(ちゅうい)ください。

    If you take your eyes off of your child, they might get lost without you even noticing. Please, be careful.

  • いつのまにかもう1(ねん)()ってしまった。

    Without me realizing it, another year has passed (all too soon).

  • 帽子(ぼうし)(かぶ)ってないといつのまにか風邪(かぜ)()だからきちんと帽子(ぼうし)(かぶ)って。

    If you do not wear a hat, you will catch a cold before you know it. That's why you should put on a hat.

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いつの間にか – Grammar Discussion

Most Recent Replies (6 in total)

  • SevenZeven



    I couldn’t remember this construction at all, so I tried 「知らずに」 as a blind shot in the dark. Does the sentence make any sense like that?

  • wrt7MameLZE33wlmpCAV


    I think you would be understood saying 知らず. いつの間にか seems to fit the sentence just a little better because of the nuance of surprise. In my opinion, it’d be fair for there to be a hint that 知らず is not what’s expected because that seems like a good guess to me.

  • Fuga


    Hey @SevenZeven !

    As @wrt7MameLZE33wlmpCAV said, you probably would be understood, but 知らずに here sounds extremely unnatural. 知らないうちに is a lot more natural. However, 知らないうちに and いつの間にか has a difference in nuance.

    知らないうちに has a nuance that you had some control, or was aware about what was happening, but not entirely sure how or why it happened. いつの間にか has the nuance that something happened without warning because you were not paying attention to it or you couldn’t pay attention to it (due to an external or internal force). いつのまにか has the nuance of ‘it happened in a blink of an eye’, but 知らないうちに does not.


    Without noticing they have come to call me “Pochi.”
    Nuance: I just started to notice that people are calling me ‘Pochi’. Because I wasn’t paying attention to what people were calling me, it seems to...

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