How to tell them apart
ないことはない uses a double negative to admit that something is in fact the case, often softening it with a follow-up like but his blood pressure is a bit high. わけではない directly denies an implication or assumption, saying it is not that X is true. The test is whether you are confirming a negative question (元気じゃないことはない) or rejecting someone's inference (そういうわけではない). Swapping them sounds odd because ないことはない affirms while わけではない denies.
- ないことも / はない Use ないことはない when you confirm a negative question by admitting the positive, then add a reservation.
- わけではない Use わけではない when you deny an implied meaning or assumption that someone has drawn.
| Grammar point | Meaning | JLPT level |
|---|---|---|
| ないことも / はない naikotomo hanai | it's not that... not; there are times when... | N3 |
| わけではない wakedehanai | It is not the case that; not always so | N3 |
ないことも / はない naikotomo hanai
it's not that... not; there are times when...
You can use ないこともない and ないことはない to soften a negative into a weak affirmative, meaning it is not completely untrue or impossible. Attach こともない or ことはない to the nai-form of verbs and i-adjectives, as in 行かないこともない or 寂しくないことはない, and use ではないことはない after nouns and na-adjectives. Use も when you mean something occasionally happens, and use は for a lasting state or feeling where occasional occurrence does not fit.
-
たまに一人で映画を見ないこともない。
I do watch movies alone sometimes.
-
一人暮らしは寂しくないことはない。
It's not that living alone isn't lonely.
わけではない wakedehanai
It is not the case that; not always so
わけではない denies a conclusion or weakens a claim to mean it is not the case that something holds. It is often used to correct a misunderstanding or to show that something is not always true, as in 高い店がおいしいわけではない. It follows the plain form, such as する, しない, した, i-adjectives like 高い, na-adjectives with な like 静かな, and nouns with である or だ, as in 学生であるわけではない. The tone is explanatory and neutral, and care is needed to keep the negation on わけ rather than making the predicate itself fully negative.
-
そういう類いのものは、どこにでもあるわけではない。
That kind of thing can't be found just anywhere.
-
しかしこれは昔から常にそうであったわけではない。
However, this has not always been true.
ないことも / はない and わけではない are both JLPT N3 grammar points that Japanese learners often mix up. This page compares them side by side on meanings, usage and example sentences, so you can tell them apart.