What's the difference between 成人 and 大人 ?

  • 3
    I'd say it's the same as "grown up" vs. "adult" in English. "Adult" is objective (legal after a certain age) whereas "grown up" is subjective (how you act, lifestyle, etc.) Just a hunch, so I'll leave it as a comment.
    – istrasci
    Commented Sep 3, 2011 at 6:08
  • 4
    (But which is which?)
    – Matt
    Commented Sep 3, 2011 at 7:02
  • I found something on my Japanese synonyms dictionary, but I can't understand it all so I don't know how to parse it here in order to help you. :D
    – Alenanno
    Commented Sep 3, 2011 at 8:22
  • @Alenanno ok no worries =) btw you could just post it here if you wish, maybe someone could help intepret it.
    – Pacerier
    Commented Sep 3, 2011 at 14:31
  • @Pacerier: There is a table in it. Should I post it as an answer? :)
    – Alenanno
    Commented Sep 3, 2011 at 14:50

3 Answers 3


成人 is a very specific term and refers to persons who reached the age of 20 and above. It's derived from the definition of the Japanese law, which says "年齢二十歳をもって、成年とする".

You used to get drafted and taxed after this age. In today's context, it's the legal drinking/smoking age.

大人 is a more lax term and usually means persons that are older than around 18 - 25 (depends on the context/speaker).

大人 is also used to mean "mature". For example, a toddler can be 大人 like this:

A: 大樹君、3歳なのにお寺が好きなんだって!
B: 大人~(笑)

You can't do this with 成人. It's also more formal than 大人 so it's much more common to use 大人 in everyday speech. Also 成人になる specifically means "to turn 20". 大人になる usually means "to become mature".

芳一は来年成人になる -> OK
芳一は来年大人になる -> Weird
美緒もだんだん成人になってきたなぁ -> Weird
美緒もだんだん大人になってきたなぁ -> OK

  • Cool, I think I sort of get your meaning. Do you mean that 成人 is more of like "of age" and would vary between countries (some 18, some 20, some 21) ?
    – Pacerier
    Commented Sep 3, 2011 at 14:34
  • 3
    Although 成人 often means 20 years old and above, it is not always the case. For example, 成人映画 usually refers to a movie for which no one under 18 is admitted. Commented Sep 3, 2011 at 16:00
  • @Tsuyoshi that would definitely make it more like the English "of age", then. Commented Sep 4, 2011 at 8:59
  • 2
    @Pacerier: Yep. You could say アメリカでは21歳から成人となります。 Commented Sep 5, 2011 at 0:56
  • @Enno ok thx for the help
    – Pacerier
    Commented Sep 5, 2011 at 11:26

This is what I found in my dictionary. Considering I'm not actually an expert, or even an intermediate at reading Japanese, it might not be the definite answer you're looking for.

But since it was impossible to post it as a comment, I'm writing it as an answer:

おとな 【大人】
せいじん 【成人】

☞ アダルト
成長して一人前になった人。【英】 an adult

大人 ▽体だけは大人だが、まだ頼りにならない▽年は若いがなか

enter image description here
用例組み合わせ:"◯"=可, "△"=避けた方が無難, "—"=不適当



反対語大人⇔子供 成人⇔未成年


The thesaurus is "Tsukaikata no Wakaru Ruigo Reikai Jiten" (使い方の分かる類語例解辞典), which is provided by the Japanese publisher Shogakukan.

  • 1
    I'm hardly good at reading Japanese too but from what I can make out, I think 成人 refers to the state of a person after he has passed the "socially accepted age by the community to be responsible (for his own actions)". It is "objective" whereas 大人 could sometimes be "subjective" in the same sense we use the word "mature". Thanks for the answer =D I'd let someone else more advanced to edit/translate it.
    – Pacerier
    Commented Sep 4, 2011 at 23:50
  • 2
    Not sure how copyright works in this case. At minimum you should probably post the source ;) Commented Sep 5, 2011 at 1:04
  • @Enno: It is from the dictionary which is standard on my computer. I linked the name of the Thesaurus and the company page on Wikipedia.
    – Alenanno
    Commented Sep 5, 2011 at 7:57

成人 means adult or to mature or to grow up. 大人 just means adult.

You may use 大人 as "Only adults can see this film" I'd treat it like a noun. 大人だけこの映画が見える。

For 成人 you may use it in a similar context as above or you can say someone has grown up. In the next example. Sandra has grown up to be a beautiful woman.


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