Translation guide
Expressing doubt or skepticism in Japanese involves a range of words and patterns, from simple adjectives like 疑わしい to verbs like 疑う and sentence-final particles. The most natural choice depends on whether you are doubting a fact, a person's honesty, or expressing personal uncertainty.
Expressing that something seems untrue or questionable
An i-adjective meaning 'doubtful' or 'questionable'. Used to describe a statement, claim, or situation that seems suspicious or hard to believe.
彼の話は疑わしい。
His story is doubtful.
A pattern meaning 'it is doubtful whether...'. Used to express skepticism about a proposition.
彼が来るかどうか疑わしい。
It's doubtful whether he will come.
An i-adjective meaning 'suspicious' or 'shady'. Often used for people, situations, or things that seem untrustworthy or dubious.
あの人は怪しい。
That person looks suspicious.
Expressing that you do not trust someone or believe what they say
A verb meaning 'to doubt' or 'to suspect'. Used when you question someone's truthfulness or motives.
私は彼の言葉を疑っている。
I doubt his words.
Literally 'do not trust'. A straightforward way to say you don't believe someone.
彼の言うことは信用しない。
I don't trust what he says.
Conveying that you are not sure about something, often about your own thoughts or future events
A common pattern meaning 'I don't know whether...'. Expresses uncertainty about a fact or outcome.
明日雨が降るかどうか分からない。
I don't know whether it will rain tomorrow.
Means 'might' or 'maybe'. Used to express a possibility while implying doubt.
彼は来ないかもしれない。
He might not come.
A casual phrase meaning 'I wonder' or 'I'm not sure'. Often used in spoken Japanese to express mild doubt.
彼が本当に来るかどうか、どうかな。
I wonder if he'll really come.
Expressing that you suspect something is wrong or someone is guilty
A verb meaning 'to suspect' or 'to be suspicious of'. Stronger than 疑う, often implying a gut feeling.
彼の行動を怪しんでいる。
I'm suspicious of his behavior.
A noun meaning 'suspicion' or 'doubt', often used in formal contexts like scandals or investigations.
English 'I doubt' is often translated as 疑う, but in many cases, 〜かどうか分からない or 〜かどうか疑わしい is more natural. Using 疑う directly can sound like you suspect someone of wrongdoing.
疑わしい is more about logical doubt (doubtful), while 怪しい is about a suspicious appearance or feeling (shady). Use 怪しい for people or situations that seem untrustworthy, and 疑わしい for statements or facts that seem questionable.
彼の話は疑わしい。
I doubt his story.
彼女は疑わしそうに私を見た。
She looked at me with doubt.
There are suspicions about that politician.