In the chapter Things that should be a certain way of Tae Kim's guide, the author states that in order to express the expectation of something not happening, one should use something like 「~はずがない」. I was wondering if the Japanese language distinguishes phrases like "I don't expect him to come" vs. "I expect him not to come"? In other words, are both of these acceptable:

  • 彼は来るはずがない
  • 彼は来ないはずだ

If not, are there other constructs to express this?

3 Answers 3


Both are acceptable.

But note that each of them has a different meaning. And these meanings are subtly different.


= We have the expectation that he won't come.


= We do not have an expectation that he is coming.

The difference here is that we are stating our expectation in the first case. In the second, we are negating an expectation. In the first the expectation is negative. In the second, the expectation is positive. Turned into a chart:

                    ~ないはず       ~はずがない      ~ないはずではない

Expectation         -                +                  -
Statement           +                -                  -
Net Statement       -                -                  +

来るはずがない is understood to be stronger than 来ないはずです in terms of the strength of our belief he wont' come by native speakers.


= We have no reason to expect he will come.



= It's no wonder he doesn't come

  • 3
    明鏡国語辞典 says: 「賛成するはずがない/賛成しないはずだ」では、前者の方が意味が強い(前者は賛成の可能性が皆無、後者は可能性を残す)。
    – user1478
    Feb 15, 2014 at 4:32
  • Thanks Snailplane. It's all somewhere in my head from a grammar class a while ago. It just ain't coming out right!
    – virmaior
    Feb 15, 2014 at 4:34
  • Thanks! I wish I could mark two answers, because Tim's is also great. I decided on this one - the truth table won me over :-)
    – waldrumpus
    Feb 15, 2014 at 18:06
  • 「~~は来ないわけです」には色んな意味・使い方があります。eg「(どおりで)~~さんは来ないわけだ。」「(つまり)~さんは来ないわけです。」「(いくら待っても)~さんは来ないわけです。」etc...
    – user1016
    Mar 31, 2014 at 15:52
  • @Chocolate どこかわけとはずが交換できないと覚えていますが、それはどのケースですか。(現在その教科書はほかのアパートにある)
    – virmaior
    Apr 1, 2014 at 0:32

I am going to offer a simpler explanation making reference to the previous answers and comments (avoiding any consideration of changing は or が ) :

Both are acceptable, both indicate the actor is not expected to visit but there is a difference which can be shown by the following which are quite close to the normal translation of はず into standard English:

彼は来ないはずです。| I expect he won't come.

彼は来るはずがない。| I have no expectation of him coming [at all].

As explained by 明鏡国語辞典 (in Snailplane's comment), the second case is much stronger because the speaker is excluding any possiblity of the actor coming. (皆無=>"There is no chance he is coming.")


This was not part of the question but it is a worthwhile comparison:

はずがない and わけがない are taught as interchangeable. I rationalise this on the basis that わけ is used to convey circumstances or a reason, as follows:


He has no reason to come.


He is not coming under any circumstances.

(~There are no circumstances under which he will come.)

=> I have no expectation of him coming [at all].

The expression 「彼は来ないわけです。」, on the other hand, might be used to explain: "That is because he is not coming.", or depending on the situation: "Yes but he is not coming."


I think those two sentences are equally acceptable. As for the other way, 彼が来るはずはない. In 彼は来るはずがない, "he" is the point of attention, and this expression implies other persons except him will come, like 彼女は来るはず. In 彼は来ないはずだ, "won't come" is the point of attention, and this implies he will do other actions, like 彼は他の場所へ行くだろう. In 彼が来るはずはない, "彼がくるはず" is a noun clause.

  • I don't think its merely a matter of attention though I think the jist can often work out to be the same.
    – virmaior
    Feb 15, 2014 at 4:07

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