For example:


A: 同じです (I said)

B: 同じくです (A native Japanese speaker said)

The 終止形 of 同じく is 同じい, but it seems they have the same meaning

Is there any difference between them, anything makes A and B sound different?

  • In the first place it's a little weird to respond to something like that with 同じ like you might do with 'same' in somewhat slangy English; 「(それ)わかる!」is more natural and also feels a little slangy to me
    – Angelos
    Aug 1, 2022 at 15:26
  • 1
    Where did you encounter 同【おな】じい? I have never heard this myself, and from what I've seen in references, I don't think it ever existed. Separately, assuming that 同【おな】じい does exist, this would presumably be the 連体形【れんたいけい】 or attributive form (must be followed by a noun), whereas 同【おな】じく would be the 連用形【れんようけい】 or adverbial form (usually followed by a verb or other adjective; in your sample, the adjective is implied from context to be the earlier ほしい). Aug 1, 2022 at 16:35
  • @EiríkrÚtlendi Hmm? Almost all monolingual dictionaries have an entry for 同じい Aug 1, 2022 at 21:51
  • 1
    I can naturally understand 同じゅう as ウ音便 of 同じく, but 同じい strikes me as being "strange" rather than literary or archaic...
    – naruto
    Aug 2, 2022 at 0:51
  • 2
    @naruto Personally I only find it natural in the usage that 三省堂国語辞典 lists: [・]おなじ ・い[同じい]⦅形⦆ 〔文〕同じだ。等しい。 「知らないと言うに━」, while the usages in 大辞林 and 大辞泉 feel unfamiliar to me Aug 2, 2022 at 4:03

1 Answer 1


In that context, 同じです and 同じくです work the same, though the former is more common. But that does not mean they are always interchangeable.

同じ and 同じく are not regular adjectives. There is no such an i-adjective as 同じい*, and 同じく is a fixed adverb meaning "likewise" or "similarly". 同じく is typically used when repeating the same opinion or in place of the same word.

*Actually a large monolingual dictionary has an entry for 同じい as an i-adjective, but don't use it in modern standard Japanese. 同じく is the only allowed form.

  • A「私は反対です。」B「同じく私も反対です。」
    A: "I disagree." B: "I disagree, too."
  • A「大阪から来た田中です。」B「同じく佐藤です。」
    A: "I am Tanaka from Osaka. B: "I am Sato, also from Osaka."

同じくです is not very common, but it's "Same here" or "Ditto". Thus you cannot use 同じく in the following example:

  • A「XとYは違いますか?」B「同じです。」
    A: "Are X and Y different?" B: "They're the same."

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