modality N1 uncommon written
〜ないとも限らない — it's not necessarily not ~
〜ないとも限らない ・ ないともかぎらない
Builds on ない形
Meaning
- it's not necessarily not ~ / there's no guarantee that ~ won't (happen) / ~ might well happen — warns that a (usually unwelcome) possibility cannot be ruled out
Key sentence
この地域でも、地震が起きないとも限らない。
Even in this region, it's not as if an earthquake couldn't happen.
Formation
| Attaches to | Form | Example |
|---|---|---|
| Verb / clause (ない form) + とも限らない | V(ない) + とも限らない | 失敗しないとも限らない / 来ないとも限らない |
When: Written / cautious register; typically warns of a risk and motivates a precaution.
Examples
鍵をかけておこう。泥棒が入らないとも限らない。
Let's lock up — you can't rule out a burglar getting in.
今は元気でも、いつ病気にならないとも限らない。
You may be healthy now, but there's no guarantee you won't fall ill someday.
Easily confused with
とは限らない とは限らない denies a general assumption ('not always / not necessarily ~'); ないとも限らない is the double-negative twist — 'you can't be sure it WON'T happen,' flagging a lingering possibility. ないこともない ないこともない hedges toward a mild yes ('it's somewhat possible / true'); ないとも限らない warns that a negative outcome can't be excluded ('it might well happen').
See 〜ないとも限らない in real sentences
Jengo shows 〜ないとも限らない the way you actually meet it: inside real Japanese sentences, so it sticks instead of staying an abstract rule.
Study it in JengoSources Compiled from published Japanese grammar references.