When talking to Japanese people they tend to use 一緒 when describing things that are the same. I have always thought that 同じ should be used when describing things that are the same.

Is 一緒 just an informal way of 同じ or there is more to it?

For example:

それはこの意味と一緒ですよね。That has the same meaning as this, doesn't it?

私たちはお休みの日が一緒ですね。Our days off are the same.

花子と私は去年一緒のクラスにいました。Hanako and I were in the same class last year.


1 Answer 1


There's a very interesting article on exactly this topic. My explanation below is a brief summary of said article.

同じ has two meanings:

  • (Meaning 1) Among two or more things, a specific aspect is seen to be equal. For example, 「AとBは同じ大きさだ」.
  • (Meaning 2) One thing only is referred to as being the same. For example, 「毎日同じ靴を履いて外出する」.

一緒 can be used interchangeably for Meaning (1) above, but not for Meaning (2).
All your sentences are examples of Meaning 1, wherein two things are compared and found to have an equal aspect (That+This, Same meaning/Me+You, Same day off/Hanako+Me, Same class).

For Meaning (1) you can have sentences like 「あなたの映画の好みは、私と一緒だ」 or 「あなたの映画の好みは、私と同じだ」. However, 一緒 has additional usages which differentiate it from 同じ. For example, it is used to mean 'doing the same thing', referring to actions or behaviour. Sentences which use 一緒に including other people use that meaning (一緒に映画に行きませんか?). It can also be used to indicate that two events happen at the same time (クリスマスと誕生日を一緒にお祝いする), or putting things together (袋に一緒に入れる). For these additional meanings, 同じ cannot be used interchangeably, only for Meaning (1).

  • Thank you. When you say "doing the same thing", you mean "doing [something] together", don't you?. To me, the latter usage where 一緒 is not interchangeable with 同じ is simply "together", not "same", so there wouldn't be a confusion.
    – jarmanso7
    Jul 29, 2020 at 12:52
  • I mean, you can for example be studying at your home, while I am studying at my home. We could say we are "doing the same thing", but we couldn't say we are "studying together", and I suspect that we couldn't say 一緒に勉強している in such situation, could we?
    – jarmanso7
    Jul 29, 2020 at 12:54
  • Yes, it includes the idea of doing the activity together with someone. If we are in different places but happen to be doing the same activity, 一緒に would not be the correct way to express it.
    – kandyman
    Jul 29, 2020 at 12:57
  • In other words, we can use 同じ + noun while we can't use 一緒 + noun right?
    – Zenitsu
    Jul 30, 2020 at 0:01
  • 1
    @Zenitsu no. You are pointing out a difference in syntax between 同じ and 一緒, but what we are discussing here is the difference in meaning. Note that in the last example sentence 一緒のクラス, 一緒 is modifying the noun クラス. So 一緒 can be used to modify a noun, provided you join them by using の. If you used 同じ in that example sentence, it would be 同じクラス without the の. But both words can be used to modify a noun.
    – jarmanso7
    Jul 30, 2020 at 6:25

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