Text books normally teach that the negative of です is じゃありません. However it seems very common to hear native Japanese use じゃないです.

Is this slang or somehow less correct than じゃありません? Would it be marked as incorrect in a JLPT exam?

If they are both equally correct why is じゃありません taught to beginners? (To me じゃないです seems simpler for a beginner to remember.)

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    I was under the impression that the negative of です is ではありません Commented Aug 10, 2011 at 12:30
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    @Nicolas: That's right. じゃありません is a shortened form of ではありません. So ではありません and ではないです are more formal than じゃないです and じゃありません。But in answer to the question, they are both correct. I don't know that one is more 'correct' than the other. じゃないです is certainly more commonly spoken than じゃありません。Most common in speech is simply じゃない - but it's obviously less formal / polite too. Commented Aug 10, 2011 at 12:55
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    I remember when I was taking Japanese 101, my professor saw Nakama teaching じゃありません as the polite negative and she literally recoiled in horror, after which she made it clear that we were to use ではありません.
    – Kaji
    Commented Mar 31, 2014 at 5:02

4 Answers 4


I read an interesting paper on this very topic a few months ago. Let's see…ah, here it is:

A Discussion of the Polite Negative Verb Forms masen and nai desu (PDF, Japanese)

This paper by Kayoko Tanaka was presented at the eighth annual conference on Japanese language education research at Nagoya University in 2010. Ms. Tanaka, using sentences drawn from a survey of spoken Japanese, draws the following contrast:

~ません (in spoken Japanese)


masen has a strong sense of formality, and often expresses the speaker's firm denial. Also, it is often used to add a sense of assertion or in emphatic constructions. This is thought to arise from the influence of the linguistic form (where the order is polite mase + negation n), in which the intent of negation appears stronger than the politeness. From this the speaker can draw the listener's attention to the negating function. If we assume that expressions which appear nearer to the end of the sentence leave stronger impressions, the negating function of masen leaves a strong impression. (emphasis mine)

~ないです (in spoken Japanese)


nai desu is often used in spoken Japanese. As indicated by Noda (2004), the effects of this construction are such that it is often used in concert with sentence-ending particles, and that it is easily joined with the (verb) + shiteiru form. This is thought to arise from the influence of the linguistic form (where the order is negation nai + polite desu), in which the level of politeness appears stronger than the negating function. From this the speaker can draw the listener's attention to the level of politeness. If we assume that expressions which appear nearer to the end of the sentence leave stronger impressions, the politeness of nai desu leaves a stronger impression. Also, it is further thought that this may have the effect of softening the speaker's strong assertion of a negative expression. (emphasis mine)

So basically…

~ません and ~ないです are semantically equivalent, but ~ないです is softer and less insistent. If you need to give a firm denial with no wiggle room, go with ~ません. But since this level of bluntness can be inappropriate in some situations, ~ないです is there if you need it.

Also, this applies to every negative sentence (not just those ending in a form of です):




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    An important fact about this paper is that it only discusses 自然談話 (spoken language?) (see section 2). According to the results cited in the paper, ません is overwhelmingly more common than ないです in written text. Commented Aug 10, 2011 at 16:21
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    Interesting. I asked some Japanese friends and teachers about this a while back, and they gave me exactly the opposite answer.
    – rintaun
    Commented Aug 11, 2011 at 0:13
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    @DerekSchaab I would argue that most linguists are primarily concerned with the way a language is actually spoken. ~ないです is perfectly valid from a linguistics standpoint. Linguists often do deal with the "rules" of language, but this is in the sense of trying to find a way to describe the language rather than trying to prescribe how it should be used. In fact, many linguists are concerned with the various dialects of a language even though they do not match the "standard" dialect. Commented Sep 28, 2011 at 23:06
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    @DerekSchaab - where do you find all these papers?
    – istrasci
    Commented Sep 29, 2011 at 14:02
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    @istrasci: Google. One trick is to put filetype:pdf into the query, which biases the results toward academic papers (usually published in PDF format). Commented Sep 29, 2011 at 14:17

Disclaimer: I'm neither a native speaker nor a linguist so this answer of mine is entirely my opinion and theory as a beginner, which may not be appropriate here but I wanted to share it anyway.

To me ではないです or じゃないです is like turning a negation statement into polite:

Xではない (a negation statement) + です (make it polite)

While ではありません or じゃありません is like a polite negation of a statement:

X (a statement) + ではありません (politely negate it)

I'm not sure how it actually affects the quality of politeness of the sentences, but my guts feeling is that ではないです is slightly less elegant than ではありません due to the following reason: Making a plain negative statement polite gives off the feeling of not thinking about being polite from the beginning. It is like being forced to be polite due to the circumstances, unlike politely negating the statement which gives off the feeling that you are already thinking about being polite before being negative.

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    If you assume that ません is an unbreakable unit, then you are on the right track. But the question is: how does that lead to the difference of the nuance/usage? Or, are you assuming that there is no difference in the usage?
    – user458
    Commented Aug 10, 2011 at 13:20

じゃないです is a colloquial, uneducated way of saying じゃありません. It is not totally ungrammatical, but is not totally correct either.

My reasoning for this is because it is not the shortest way of saying it. Assuming that ない results from obligatory deletion of ara in Tokyo dialect and that the i-ending of an i-adjective is an obligatorily replaced form of ku aru, the fully expanded form of the two expressions are:

ないです (7 morphemes)
ar-ana-ku ar-u des-u

ありません (4 morphemes)

Using ありません is much shorter. For those people who do not use じゃありません, the negative morpheme en, which is conditioned to be used only with politeness, is either blocked temporarily or is not known by the speaker.

I am interested in hearing other accounts of this contrast.

To answer ento's question:

In general (in any language), a well phrased (correct) sentence has to be the shortest among the alternative strategies that have the exact same meaning (including connotation, naunce, etc.). This is a genaral, basic fact about language, and is observed at various levels (word, sentence, discourse). For example, in English, it is not fully appropriate, unless there is a special connotation or purpose, to say sentences like

I am doing eating of a sandwich
I am feeling sadness
It is the case that it is sunny today [As a main sentence]

because there are shorter ways of saying them with the same meaning:

I am eating a sandwich
I am sad
It is sunny today

My explanation above handles ないです vs. ありません in relation to this basic principle. This is about awkardness, appropriateness, consiceness, and correctness, but is not directly related to formality.

As for the measure of shortness, there can be several possibilities, but for symplicity, I used the number of morphemes.

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    Does it really give off the "uneducated" vibe that much? I've heard this from all types of people, including Japanese teachers and very serious university students.
    – phirru
    Commented Aug 10, 2011 at 13:04
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    @sawa: I don't understand "uneducated people cannot use じゃありません"? Cannot use it on what grounds? That they haven't learned it? I suppose it's not as commonly heard as じゃないです, so it's possible they've never learned it. But I have a hard time buying that. Commented Aug 10, 2011 at 14:39
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    Could you elaborate on the relationship between a phrase's length and its correctness, advancedness and formality? Are shorter phrases generally more correct, advanced and/or formal? I simply want to hear more because I couldn't quite follow the logic there..
    – ento
    Commented Aug 10, 2011 at 16:19
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    I think there are unexamined assumptions in your counting strategy here. Why include "ara" if it is so obligatorily deleted that no-one has used it for generations? How come -i (from -si) is replaced with "-ku aru", which is obviously a less basic (and newer!) form? If you treat "desu" as a clitic (which is what some people argue it is evolving into in spoken J., cf forms like "だったっす"), you could easily recount: na-shi desu (3) vs ar-i-(i)mas-e-nu (5). Morpheme count might actually be the reason that じゃないです is preferred by speakers with this model of the language.
    – Matt
    Commented Aug 10, 2011 at 22:31
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    @sawa Thanks for detailed reply. I should stress before I get into this that my argument is not that your model is wrong so much as it is not the only possible model. 1. So your argument is, when faced with the aru/nai vs saku/sakanai irregularity, we must attach a null morpheme to /nai/ conveying the meaning "conjugation of the verb aru"? OK, I can accept this as a model, although I don't agree that it is the only possible model, or that it must then follow that this null morpheme should be counted if we are measuring length.
    – Matt
    Commented Aug 10, 2011 at 23:16

As per my Sensei (who is a native speaker of Japanese and grew up in Tokyo), there is absolutely no grammatical difference between ~ないです and ~ません.

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    Probably your sensei meant that they are almost the same. But if your sensei really does not notice any difference, I am sorry but I think that he or she is simply insensitive to the subtlety of the language. Commented Aug 12, 2011 at 0:10
  • Updated answer to be more accurate.
    – Murphy
    Commented Aug 12, 2011 at 6:31
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    I do not think that changing “difference” to “grammatical difference” makes your sensei’s assertion any more accurate. As other people correctly state, ないです and ありません are different in formality and nuances. Commented Aug 12, 2011 at 12:40

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