Translation guide
The English word "doubt" covers a range of meanings from uncertainty and skepticism to suspicion and disbelief. In Japanese, different words and expressions are used depending on whether you are expressing personal uncertainty, questioning a fact, suspecting someone, or stating that something is unlikely. This guide helps learners choose the most natural Japanese expression for each nuance.
Expressing that you are not sure about something, or that you have doubts about your own knowledge or ability.
A general noun meaning 'doubt' or 'question'. Often used in phrases like 疑問に思う (to have doubts about something). It is neutral and can be used in both spoken and written contexts.
I have doubts about his explanation.
Literally 'have no confidence'. This is the most natural way to express self-doubt about one's ability or knowledge.
I doubt I can pass the exam.
Means 'to think something is doubtful/questionable'. Used when you are skeptical about a statement or claim.
A set phrase meaning 'half in doubt, half believing'. Used when you are not fully convinced.
I was in doubt about that news.
Expressing that you think something may not be true or correct.
Expressing that you believe someone may have done something bad or dishonest.
Saying that you think something probably won't happen or isn't true.
A pattern meaning 'I can't think that...' or 'I doubt that...'. It is a natural way to express disbelief or strong doubt about a statement.
Expressing hesitation or reconsideration about a choice or plan.
Means 'to have hesitation/doubt' about a decision. It implies you are wavering or unsure.
English speakers often say 'I doubt it' as a casual response. In Japanese, directly translating this as それを疑う sounds unnatural and overly strong. Instead, use phrases like そうは思わない (I don't think so), それはないと思う (I don't think that's the case), or 多分違うと思う (I think it's probably not).
疑う (utagau) often implies active suspicion or distrust, especially toward a person. 疑問に思う (gimon ni omou) is more about intellectual doubt or questioning the validity of something, without necessarily implying bad intent. Use 疑問に思う when you simply find something questionable or unclear.
There is no doubt that he is guilty.
I have doubts about that plan.
I think what he says is a bit doubtful.
The most direct verb for 'to doubt' or 'to suspect'. It can be used for doubting facts, statements, or people's honesty. Be careful: when used with a person, it often implies suspicion of wrongdoing.
I doubt his words.
I doubt the truth of that story.
Means 'to think something is suspicious/doubtful'. More colloquial than 疑う and often used in everyday conversation.
I doubt that person's excuse.
A phrase meaning 'doubtful whether it's true'. Useful when you want to express skepticism without directly accusing someone.
I doubt whether that information is true.
The same verb as above, but when the object is a person, it strongly implies suspicion of a crime or misdeed. Often used in the passive form 疑われる (to be suspected).
The police suspect him of being the culprit.
He was suspected of lying.
A verb meaning 'to suspect' or 'to be suspicious of'. Slightly more formal and less common in casual speech than 疑う.
I am suspicious of his behavior.
A noun meaning 'suspicion' (often in a legal or formal context). Used in phrases like 嫌疑をかける (to cast suspicion on someone).
He is under suspicion of theft.
I doubt he would do such a thing.
I doubt it will rain tomorrow.
A strong expression meaning 'there is no way that...' or 'it cannot be that...'. It conveys a high degree of certainty that something is not true.
I doubt he doesn't know. (lit. There's no way he doesn't know.)
Similar to はずがない, meaning 'there is no reason that...' or 'it's impossible that...'. Slightly more logical/rational in nuance.
I doubt she would make such a mistake. (lit. There's no reason she would make such a mistake.)
I still have doubts about whether to accept that job.
Similar to 迷い, but often implies a more emotional hesitation or reluctance.
I have doubts about telling him the truth.
I doubt if he will come.