I've often seen and heard the expression 〜と知る(知っている). When I think about it, it makes sense in the context of the quoatation-と, like with 〜と言う or 〜と思う. It seems like it means "Know that 〜".

ミユキちゃんが結婚したと知ってる? → Did you know that Mikyuki got married?

However, the few times I've tried to use it, I was told I was using it incorrectly, and that I should instead use 〜こと/のを知る.


So what are the rules for using 〜と知る? Do 〜と知る and 〜こと/のを知る have different meanings and rules (they seem the same to me)?

Update: I've found quite a few examples from my Bible. It's the 新共同訳 version, and I was able to search it here. I searched for ~と知る, ~と知って, and ~と知った. Here are a couple examples:

  • 「群衆は、イエスも弟子たちもそこにいないと知ると、自分たちもそれらの小舟に乗り、イエスを捜し求めてカファルナウムに来た。」 - ヨハネによる福音書 / 6章 24節
  • 「けれども、人は律法【りっぽう】の実行ではなく、ただイエス・キリストへの信仰によって義とされると知って、わたしたちもキリスト・イエスを信じました」 - ガラテヤの信徒への手紙 / 2章 16節
  • 「ヨナタンは言った。『そのような事は決してない。父があなたに危害を加える決心をしていると知ったら、必ずあなたに教えよう。』」 - サムエル記上 / 20章 9節
  • 3
    I would interpret all of these as と(言うのを). In colloquial this would be って.
    – Dono
    Commented Apr 20, 2012 at 3:30

2 Answers 2


The examples are very interesting. It looks like, whenever と知る can be used, it means "find out" rather than "know". Another way to say this is, whenever と知る can be used, you can replace the verb with 分かる. With "find out", you cannot have duration, in other words, you can say:

I knew that theorem for two days, (but I forgot it).

but you cannot say

* I found out that theorem for two days.

the aspectuality matters. Applying this to Japanese, you can use と知る with a simple tense (under which 知る means "find out"):


but not with perfect (under which 知る means "know"):

* 昨日から、みゆきちゃんが結婚したと知っている。

And indeed this makes sense because (similar to "to") implies the goal of change of location/state of something. Finding out something is a change of state, but knowing something is not.

  • 1
    This is a great answer. What do you think about "と知りながら" (e.g. "奥さん自身嘘と知りながらそうおっしゃるんでしょう")?
    – Matt
    Commented Apr 20, 2012 at 12:47
  • 3
    I think that you are approaching some truth, but I do not completely agree with what you wrote. For example, in 来週君が来る[と/ことを]知っていれば、この時期に出張なんか入れなかったのに, both と and ことを sound natural to me although it uses the form 知っている. Commented Apr 20, 2012 at 13:59
  • @TsuyoshiIto I agree with your judgement. Maybe my description about ている was wrong. But in your example, it can be replaced with 分かる, so that part of my answer is correct, I think.
    – user458
    Commented Apr 20, 2012 at 15:36
  • @TsuyoshiIto: then does my original made-up example sound natural at all to you? ミユキちゃんが結婚したと知ってる?
    – istrasci
    Commented Apr 23, 2012 at 5:33
  • @istrasci: I cannot explain why, but ミユキちゃんが結婚したと知ってる? does not sound very natural to me. It should be ミユキちゃんが結婚した[の/こと]を知ってる?, as others noted. Commented Apr 23, 2012 at 10:10


This sentence is grammatically correct but not natural.


This one is natural. In modern Japanese conversation, it does 促音便化 in this case. But, the old style is also still in use even in conversation.


So, here is the problem. "知ってる?" is quite informal, but "したと" is quite formal. That difference makes us uncomfortable.

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