This sentence ending has started to creep up more and more in my current Japanese classes, and I'm still a bit unsure what all it can mean, how to use it, or even when I should think to use it. My Japanese teacher in a previous class mentioned that it can be used to "give emotion" to a statement or to inform the listener of new knowledge. Something along those lines. But I'd love a more formal explanation.

  1. What does it mean?
  2. Is there a particular usage pattern to follow?
  3. What are some good examples of the various uses of this pattern, and how would they compare to the same sentences, only without んです?

のだ (んだ, のです, んです, or の) seems to create an information deficit. There was an article written by Derek Schaab about this.

The の here is called a formal noun. It is very often translated to "It is that~", "the case", "the situation" or "the fact". When used to end a sentence, it may imply that it is an explanation to some previous context (filling up the information deficit). When used to ask a question it begs a deeper explanation over a superficial reply (creating an information deficit).


  1. 私は猫が好きだ - I like cats

  2. 私は猫が好きなのです。 - It is that I like cats

For 1, it is a neutral statement that just says that you like cats.

For 2, it fills in a blank with the fact that you like cats as some sort of explanation. For example, if you got distracted by a cat and went out of your way to pet the cat, and your friend who was with you at the time gave you a quizzical look. You may reply 私は猫が好きなのです。 as an explanation to your behaviour to fill in the information deficit of your friend.

You can also use のです to immediately fill in an information deficit that you think the listener should have:

  • 今日は出かけられない。宿題がたくさんあるのです。 - "I cannot go out today. (The reason being that) I have lots of homework.

のです can also be used when no information is shared by the speaker and listener, and is not used to express reason or an explanation. When used as such, the speaker speaks as though the information was shared and the effect this creates is to involve the listener in what the speaker is talking about, or to create an emphasis on what the speaker is talking about (by means of creating a perception of information deficit of the listener).

(heefske has done a better job of explaining this in another question the summary is that it builds rapport by showing emotional investment in the issue.)

Usage pattern:

  • Verb + のです

    するのです - it is that ~ is/will be done

  • Verb(past) + のです

    したのです - it is that ~ was done

  • い-Adjective + のです

    高いのです - it is that it is expensive

  • い-Adjective(past) + のです

    高かったのです - it is that it was expensive

  • Noun + な(attributive だ) + のです

    猫なのです - it is that it is a cat

  • Noun + だった(past だ) + のです

    猫だったのです - it is that it was a cat

  • Noun(adjective) + な(attributive だ) + のです

    静かなのです - it is that it is quiet

  • Noun(adjective) + だった(past だ) + のです

    静かだったのです - it is that it was quiet

  • 1
    Can you elaborate a bit more (perhaps with an example) on your last paragraph? I'm not sure I fully understand. Thanks for the rest, though!
    – user1316
    May 1 '12 at 18:18
  • Do you have a reliable source that states that んだ and のだ are always equal? I don't think that they are. For example I have never once heard のだ used in a sentence like this the following. 本当にしたいんですけど、できません.
    – Ian
    May 2 '12 at 5:10
  • @Ian. A Dictionary of Basic Japanese Grammar, Seiichi Makino and Michio Tsutsui. Under the first bullet in the "Notes" section of the grammar entry のだ. They should be syntactically the same, except that the nuances the contraction produces are slightly different.
    – Flaw
    May 2 '12 at 5:54
  • 2
    This was explained to me as follows by a native speaker: んだ is more informal with のだ being preferred in writing. While it's not a mistake to use のだ in spoken language, you will sound "bookish", i.e. very carefully choosing your words as if reading from a previously prepared text. May 2 '14 at 13:37
  • 3
    Derek Schaab article link is broken :/
    – vadasambar
    Jun 1 '17 at 12:24

~んです is a contraction of ~のです, which in turn is the polite form of the plain/informal ~のだ (which is also seen sometimes as ~んだ.)

~のです/~のだ are used to emphasize the previous statement. According to Daijisen and Daijirin, のです emphasizes explanations of cause/reason/basis etc. In the forms of ~んですか/~のですか, it can create an emphasized or even demanding question.

See also the sci.lang.japan FAQ for more information.


One usage that I was taught and is not mentioned above for んです is to soften a question or statement.

For example

レストランに 行きたいです I want to go to a restaurant.

is a bit demanding or matter-of-fact. Changing to 行きたいんです softens this. Imagine a friend asks you about what you both should do for lunch. 行きたい sounds a bit forceful, like you will consider nothing else. The addition of ん softens it.

Consider the following:

あなたはなぜトルクに 行きたいですか? Why do you want to go to Turkey?

あなたはなぜトルクに 行きたいんですか? Why do you want to go to Turkey?

In the first example it could be somebody at immigration or other official quizzing you. In the second it could be a friend asking about your planned holiday.


助動詞「だ」の連体形「な」に準体助詞「の」が付いたもの 上昇調のイントネーションを伴って、質問の意を表す。 https://kotobank.jp/word/%E3%81%AA%E3%81%AE-347401

  • It is not really helpful to dredge up an eight year old question and give an answer that would be impenetrable to anyone who would ask such a question.
    – frog
    Oct 18 '20 at 0:48

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