I'm having a bit of trouble getting a grasp of 筋ってもん (sujitte mon) and what it's supposed to convey. Does it possibly have kind of declarative function for whatever precedes it?

Examples include:




Any help is appreciated.

  • Can you add a little more context telling us what you think it means, and why you struggle with your assumed meaning?
    – ajsmart
    Jan 30, 2020 at 13:31
  • @ajsmart I don't really have an assumed meaning.
    – evilseto
    Jan 30, 2020 at 14:11
  • If that's the case, you should know that translation requests are considered off-topic. To avoid having the question closed as such, please include evidence of your research in the body of the question. See: japanese.meta.stackexchange.com/a/799/22352
    – ajsmart
    Jan 30, 2020 at 14:12
  • 2
    Your first example is an inversion of the idiom 筋を通す, which has its own unique meaning. The latter is a usage of 〜するのが筋だ, which has a separate meaning. ってもん is pretty unrelated and is its own grammar point. Maybe you could focus your question on just one of these? Jan 30, 2020 at 14:50
  • 3
    Related (regarding ってもんだ): japanese.stackexchange.com/a/29018/9831
    – chocolate
    Jan 30, 2020 at 16:52

1 Answer 1


I suspect the core of your confusion comes from not knowing a meaning of 筋{すじ} which is applicable in both of your sentences; that is:

❺ 物事の論理的な流れ。道理。
明鏡国語辞典 第二版

This usage of 筋 is pretty idiomatic and mostly found in the expressions 筋が通る or 筋を通す, which you should be able to look up directly.

「〜するのが筋だ」 stems from that usage and basically means that 〜 is the reasonable, logical, right, or natural thing to do.

The ってもんだ is best explained in detail elsewhere (see this answer, h/t Chocolate for finding that), but it’s basically a masculine-ish way of giving a “that’s the way things are” sort of finality to your sentence. Overall, I would say that 筋ってもんだ is not so common a collocation to be able to treat it as a single unit, so it is likely better to consider them separately.


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