An example of this is that I have seen both 来週テスト and 来週のテスト. Both of them mean "next week's test".

My issue is that I have no clue when to use which or what makes them different from each other. In what situations can you leave out the の?

Edit: Just to clarify, the example I've mentioned above is one of many instances I've heard, as in when listening to shows to better grasp spoken Japanese (opposed to textbook). I'm trying to get a general guideline as to situations when one leaves it in, and when one takes it out.

  • 3
    There are certainly examples of this but I can't say I've ever heard 来週テスト except in cases like 「来週、テストがあります」
    – Angelos
    May 18, 2022 at 22:01
  • I was watching shows in Japanese to get a better grasp of non-textbook speech and they leave out the の in a lot of cases.
    – Nelunaruko
    May 19, 2022 at 9:21
  • 1
    Nouns work as adverbs sometimes just like in English (e.g. I will go to the US next year). I suppose you are picking 来週 used as adverbs as omission of の.
    – sundowner
    May 19, 2022 at 9:32
  • You know what, that's probably it actually.
    – Nelunaruko
    May 19, 2022 at 23:53

3 Answers 3


Here is the critical difference:

  • 来週の always modifies a noun (aka "adjectival").
  • 来週 always modifies a verb (aka "adverbial").

来週, 明日, 昨日 and so on do not take any particle when used adverbially. (In English, words like "tomorrow" do not take prepositions when used as an adverb, either. For example, you say "I'll do it tomorrow" rather than "I'll do it on tomorrow".)

テスト is a noun, so you should always use 来週テスト to say "next week's exam".

On the other hand, 来週テスト is simply an incorrect phrase at least in formal Japanese. In colloquial Japanese, you can understand this as an abbreviated sentence where がある is omitted (note that ある is a verb), i.e., it can be an abbreviated sentence meaning "I have an exam next week". Either way, it never means "next week's exam".

Note that Japanese is a language that strictly distinguishes noun-modifying expressions and verb-modifying expressions. See also: using の with と,で, から, まで


The meaning "来週テスト" is often used as a casual or abbreviated meaning among the general Japanese population, often in the sense of "来週テストがある"The correct grammar is "来週  テストがある" or "来週 テストがある"

来週のテスト means (a test that is next week). Or next week's test

This is very difficult for even native speakers to understand sometimes.

  • 1
    Why the downvote?
    – jarmanso7
    May 19, 2022 at 17:23
  • @jarmanso7 Did I say something wrong?
    – Qwj_38
    May 19, 2022 at 22:57
  • No, someone downvoted your answer without commenting and I was wondering why.
    – jarmanso7
    May 20, 2022 at 18:38
  • @jarmanso7 Oh, I understand, Thank you.
    – Qwj_38
    May 20, 2022 at 18:40

It's determined by the will of the speaking human. There are no rules and no guidelines. There is no need in specification, because it is used the semantics of kanji to understand the sense of the phrase. It's passed in the official documents, written speech, newspaper articles etc.

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    May 19, 2022 at 23:54
  • So, 文言文 is the language of the classic literature was used for almost all formal writing in Japan until the early 20th century, and also, during various periods In the 1900 was kana usage reforms, hentaigana (old variant forms of kana) were eliminated, though historical kana orthography (dating to the Heian period, a millennium before) was retained. SOURCE en.wikipedia.org/wiki/Japanese_script_reform
    – Alexandr
    May 20, 2022 at 1:01

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