Translation guide
How to express that an action or result happened without intent, by accident, or inadvertently. Japanese offers several adverbs and expressions that differ in nuance, formality, and whether the outcome is positive, negative, or neutral.
The action happened because the person was not paying attention or acted on impulse, not because they planned it.
Used when you do something you know you shouldn't, or something habitual, almost automatically. Often implies a slight lack of self-control.
つい食べ過ぎてしまった。
I unintentionally ate too much.
つい秘密を話してしまった。
I accidentally let the secret slip.
Used when you make a careless mistake because you weren't paying attention. Often for forgetting, overlooking, or doing something absentmindedly.
うっかり約束を忘れてしまった。
I unintentionally forgot the appointment.
うっかり電車を乗り過ごした。
I accidentally missed my stop.
Used when you react spontaneously, without thinking, often due to surprise or strong emotion. The action is reflexive.
思わず笑ってしまった。
I unintentionally laughed.
思わず叫んでしまった。
I unintentionally screamed.
Used when something happens gradually without you realizing it. Often for changes in state or accumulated actions.
知らず知らずのうちに眠っていた。
I had unintentionally fallen asleep.
The outcome was not intended; it happened due to chance or a mistake, often with a negative result.
Means 'by chance' or 'accidentally'. Neutral; can be used for both positive and negative coincidences.
偶然に彼に会った。
I met him unintentionally.
Means 'by mistake' or 'erroneously'. Used when you do something wrong unintentionally, often in formal or written contexts.
誤ってファイルを削除してしまった。
I unintentionally deleted the file.
Similar to 誤って but more casual. Used when you do something by mistake, like taking the wrong thing or pressing the wrong button.
間違って違うボタンを押した。
I unintentionally pressed the wrong button.
The person did not have the intention to cause a particular result; it was not deliberate.
Pattern meaning 'I didn't intend to ~'. Used to deny intent. Attach to the dictionary form of a verb.
傷つけるつもりはなかった。
I didn't mean to hurt you.
Casual phrase meaning 'it wasn't on purpose'. Used to deny intentionality in everyday speech.
わざとじゃないよ。
It wasn't intentional.
Formal phrase meaning 'not deliberate'. Used in official statements or legal contexts.
それは故意ではない。
That was unintentional.
The action or reaction happened automatically, beyond the person's control, often due to a physical or emotional response.
Also used here for involuntary reactions. See above.
思わず涙が出た。
Tears came unintentionally.
Can also be used for involuntary habits or urges.
つい手が出てしまった。
My hand moved unintentionally.
Means 'reflexively'. Used when the body reacts automatically.
反射的に避けた。
I dodged unintentionally.
つい is for giving in to temptation or habit (e.g., eating too much). うっかり is for careless mistakes (e.g., forgetting something). 思わず is for spontaneous, emotional reactions (e.g., laughing out loud).
ついお菓子を食べてしまった。
I unintentionally ate the sweets (couldn't resist).
うっかりお菓子を落としてしまった。
I accidentally dropped the sweets (wasn't paying attention).
思わずお菓子を掴んでしまった。
I unintentionally grabbed the sweets (reflexively).
わざとじゃない is very casual and can sound childish or defensive. For formal apologies, use 故意ではありません or 〜つもりはありませんでした.
彼を怒らせるつもりはなかった。
I unintentionally offended him.
彼女はうっかり秘密を漏らしてしまった。
She unintentionally revealed the secret.