How do I make sense of the 終助詞 もん as in


Although I have only heard it in 時代劇 speak, I guess it comes from もの, which I think should be も + の.

But what も can follow the 終止形 and what の can follow that も. Is も the same も that roughly means "also"? Is の the nominalizer の here?

P.S. I am not asking what it means, when it is used, etc. I want to know how to make sense of it grammatically. At the moment, it has also been suggested that もん・もの derived from 物, but it seems to follow different rules than what one would expect of a particle derived from a noun.

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    名詞の「もの」から来てるんだも~ん^^(物??) dictionary.goo.ne.jp/leaf/jn2/219750/m0u
    – user1016
    Apr 12, 2013 at 14:42
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    @summea But そんなもん makes grammatical sense since そんな is allowed to modify a noun. Why can we have ~だもん? For example, とき is a particle that derives from 時, but is still modified like a normal noun.
    – Earthliŋ
    Apr 12, 2013 at 22:41
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    それは「昔はよく~~したものだ」っていう時の「~たもの(だ)」では?(だって、「おいしいんだものだ」って、言いません もん 。^^)
    – user1016
    May 12, 2013 at 15:34
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    I agree. This is just 物 as "auxiliary noun", which can be constructed to もん, but is different from ~だもん...
    – Earthliŋ
    May 12, 2013 at 15:43

2 Answers 2


If I ignore semantics and discuss syntax only, I think that it went like this:

  1. もの was originally 物, a lexical noun (実質名詞), which could be modified by a relative clause ending in 用言の連体形.
  2. It was then grammaticalized into a formal noun (形式名詞), losing its literal meaning but still appearing in the same syntactic position, after a relative clause ending in 用言の連体形.
  3. After the morphophonological merger of 連体形 and 終止形, it was possible to reanalyze 連体形+もの as 終止形+もの because the two looked and sounded the same. This in turn made it possible to reanalyze もの as a 終助詞.
  4. Once it was possible for もの to be treated as a 終助詞, it became possible for it to appear after だ.

So now もの (or its contracted form もん) can appear as a 形式名詞 or a 終助詞. And of course the original word 物 is still around.


According to the book I have here "All about particles" (Chino, 1991), もの is one of the sentence final particles and its primary meaning is "because" or "reason is." Chino says もの "indicates an excuse, a dissatisfaction, or a desire to be indulged or pampared." I believe もん has the same meaning but used by mainly children and women in casual conversations.

Plain(short) form + もん Often used with んだ.








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    Thanks. I know what it means and when it is used. I would like to know why you can say ~だもん which seems to contradict the usual rule of a noun phrase modifying a noun (if that is what it is) with な (or の).
    – Earthliŋ
    Apr 12, 2013 at 22:38
  • Weird, is there anything that can syntactically follow だ at all?
    – Pacerier
    Feb 5, 2014 at 5:09
  • @Pacerier I think that some 終助詞, 接続助詞, and 間投助詞 can follow だ.
    – user1478
    Feb 5, 2014 at 5:46

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