〜とは限らない: 'Not Necessarily' / 'Not Always'
What it means
〜とは限らない is how you push back on a generalization. Someone assumes "X is always true," and you reply: that's not necessarily so. It doesn't deny X outright — it says X has exceptions.
Literally, 限る means "to limit," so 〜とは限らない is "things are not limited to (being) X." In practice, just read it as "not always / not necessarily."
高いものがいいとは限らない。
たかい ものが いいとは かぎらない。
Expensive things aren't necessarily good.
Negating the assumption 'expensive = good,' not saying expensive things are bad.
日本人だからといって、敬語が完璧とは限らない。
にほんじんだからといって、けいごが かんぺきとは かぎらない。
Just because someone is Japanese doesn't mean their keigo is necessarily perfect.
A common 〜からといって + 〜とは限らない combo.
高い店の料理がおいしいとは限らないよ。
たかい みせの りょうりが おいしいとは かぎらないよ。
The food at a pricey restaurant isn't necessarily delicious.
The key idea: you are negating a general belief, not a single specific fact. "This particular cake isn't good" is just 〜ない; 〜とは限らない is for the rule, "cakes like this aren't always good."
How to form it
Attach 〜とは限らない to the plain form of the clause you're qualifying.
| Word type | Attachment | Example |
|---|---|---|
| Verb | plain form + とは限らない | 勝つとは限らない (won't necessarily win) |
| い-adjective | plain form + とは限らない | 安いとは限らない (not necessarily cheap) |
| な-adjective | (だ) + とは限らない | 便利（だ）とは限らない |
| Noun | (だ) + とは限らない | 本物（だ）とは限らない |
For nouns and な-adjectives, the だ is optional — both 完璧とは限らない and 完璧だとは限らない are fine, with だ sounding slightly more emphatic. The verb 限る is usually written 限らない but you'll also see it as かぎらない in casual text.
Pairing with 必ずしも
Very often the clause opens with 必ずしも ("necessarily / always"), which acts like a flag telling the reader a partial negation is coming. It's the natural partner of 〜とは限らない:
モチによると、必ずしも値段が高いほうが品質がいいとは限らないそうだ。
モチによると、かならずしも ねだんが たかいほうが ひんしつが いいとは かぎらないそうだ。
According to Mochi, the more expensive option isn't necessarily the higher-quality one.
必ずしも at the front sets up the partial negation.
努力すれば必ず成功するとは限らない。
どりょくすれば かならず せいこうするとは かぎらない。
Working hard doesn't necessarily mean you'll succeed.
必ず (without し) works too in casual speech.
You can drop 必ずしも and the meaning survives, but adding it makes the "not always" nuance unmistakable.
More examples
先生でも、すべての答えを知っているとは限らない。
せんせいでも、すべての こたえを しっているとは かぎらない。
Even a teacher doesn't necessarily know all the answers.
一生懸命勉強しても、いい点が取れるとは限らないと弟が言っていた。
いっしょうけんめい べんきょうしても、いい てんが とれるとは かぎらないと おとうとが いっていた。
My little brother said that even if you study hard, you won't necessarily get a good grade.
人気のあるアプリが自分に合っているとは限らない。
にんきの ある アプリが じぶんに あっているとは かぎらない。
A popular app isn't necessarily the right one for you.
Common mistakes
- Using it to negate a specific fact. 〜とは限らない negates a generalization. "Today's weather isn't good" is 今日は天気がよくない, not 〜とは限らない. Reserve it for "X isn't always Y."
- Forgetting it's only a partial negation. It does not mean "X is false." 高いものがいいとは限らない still allows that many expensive things are good — it only denies "always."
- Adding extra particles before とは. It's plain form directly + とは限らない. Don't write 行くとはこと限らない or insert の: 行くとは限らない (✓).
- Treating 必ずしも as required. 必ずしも is a frequent partner, but the pattern stands alone: 安いとは限らない is already complete.
とは限らない vs わけではない
Both soften a statement, so they're easy to confuse:
- 〜とは限らない negates a generalization / rule: "X isn't always the case." There may be exceptions to a broad assumption. 日本人が漢字を全部書けるとは限らない ("Japanese people can't necessarily write every kanji").
- 〜わけではない denies a conclusion someone might draw in the moment: "it's not that X." 嫌いなわけではない ("it's not that I dislike it").
Rough rule of thumb: 〜とは限らない = "not always true (as a rule)"; わけではない = "that's not what I'm saying / not the case here."
Quick recap
- 〜とは限らない = "not necessarily / not always" — a partial negation of a generalization.
- Attach to the plain form; nouns and な-adjectives take optional だ.
- Often introduced by 必ずしも ("necessarily").
- It negates a rule with exceptions, not a single specific fact, and not the truth of X entirely.
Your turn
Choose the correct use of 〜とは限らない.
Start the 5-question drill →Take the full N3 〜とは限らない drill →
Frequently asked questions
What does 〜とは限らない literally mean?
限る means 'to limit,' so 〜とは限らない is 'things are not limited to being X.' In practice it means 'not necessarily' or 'not always' — X is true in general but has exceptions.
Do I always need 必ずしも with とは限らない?
No. 必ずしも ('necessarily') is a very common partner that flags the partial negation, but the pattern works on its own: 安いとは限らない already means 'not necessarily cheap.'
How is it different from わけではない?
〜とは限らない negates a generalization or rule ('X isn't always true'). わけではない denies a conclusion in the moment ('it's not that X'). Use とは限らない when you mean there are exceptions to a broad assumption.
How do nouns and な-adjectives attach?
With an optional だ: 本物とは限らない or 本物だとは限らない; 便利とは限らない or 便利だとは限らない. Both are correct, with だ sounding a little more emphatic.