I'm having a difficult time understanding the use of の-Adj in the JLPT N5 grammar examples and practice I've been studying and haven't found a good resource for finding the answer. The sentence is fairly simple but I can't tell what the purpose of the の at the end of the Adj is in it. It goes:

大きいのは いくらですか。 Ookii-no wa ikura desuka?

Does anybody have any clue? Thank you!


の in this case is a pronoun that can be translated to English as "one".

(More precisely, it's a "dependent indefinite pronoun")


大きい = "big" (adjective)

大きいの = "big one" (noun equivalent)

By applying this translation, we can see the problem that happens if we don't use の:

*大きいはいくらですか = "how much is the big" (wrong)

大きいのはいくらですか = "how much is the big one" (correct)

For more research on uses of の, I recommend reading the relevant chapters of the book "A Dictionary of Basic Japanese Grammar".

  • 1
    I'm not sure if this is a nominalizer. When you nominalize an adjective, the meaning becomes "the fact that it is Adj." e.g., 大きいのこと. Further evidence: ボブ is a noun; ボブの meaning "Bob's" is not a nominalized version of ボブ. I'm not sure what part of speech the の here is, however; I want to call it a pronoun, but it's not replacing a noun per se. The example sentences are correct, of course!
    – mamster
    Sep 23 '18 at 22:58
  • hmm yep I think you're right. I spoke too soon. I'll fix up my sloppy terminology. (fixed now) Sep 23 '18 at 23:00
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    @mamster You can have different kinds of nominalisers with different meanings - all a nominaliser is is a thing that turns something into a noun of some kind. I'd have no problem describing の here as a nominaliser; and really, it sounds much more to me like that than like a pronoun.
    – Sjiveru
    Sep 24 '18 at 14:28
  • whatever the most accurate description may be, the current description is based on the wording used in the cited reference. Sep 25 '18 at 0:35

According to "A Dictionary of Basic Japanese Grammar", page 318:

の: a nominalizer which is used when the nominalized sentence expresses a directly perceptible event. (...)

Example sentence(s):
Going to Japan is easy.


The act of talking

The expensive one

The one that was quiet


の makes a noun equivalent from a sentence. 


There is another nominalizer こと. の and こと are sometimes mutually interchangeable. For example, [日本へ行くのは簡単です。] can be restated as:

Going to Japan is easy.

  • see the comment discussion on my answer Sep 24 '18 at 3:15
  • This is very helpful. 勉強になりました。
    – mamster
    Sep 26 '18 at 10:58

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