Translation guide
Describes actions or reactions that happen without conscious control or intention. Japanese expresses this through adverbs, verb forms, and set phrases that emphasize spontaneity, reflex, or lack of volition.
思わず叫んでしまった。
I involuntarily screamed.
反射的に身を引いた。
He involuntarily flinched.
For bodily responses like flinching, sneezing, or jumping in surprise that happen without thinking.
Literally 'without thinking,' used when you do something reflexively or can't help yourself. Very common for involuntary actions.
驚いて思わず叫んでしまった。
I was so surprised I involuntarily screamed.
その映画を見て、思わず涙が出た。
Watching that movie, tears came involuntarily.
Means 'reflexively,' emphasizing a physical reflex rather than emotional impulse. Often used for dodging, catching, or protective movements.
ボールが飛んできて、反射的に手で顔をかばった。
The ball came flying and I reflexively covered my face with my hands.
Used when you do something unintentionally, often out of habit or weakness. Common for minor slips or giving in to temptation.
ダイエット中なのに、ついケーキを食べてしまった。
Even though I'm on a diet, I involuntarily ate some cake.
When feelings like laughter, tears, or anger arise despite trying to suppress them.
Pattern combining 思わず with 〜てしまう to emphasize that the action happened against one's will or better judgment.
彼の冗談に思わず笑ってしまった。
I involuntarily laughed at his joke.
Means 'unable to hold back,' used when an emotion bursts out despite efforts to suppress it. Slightly more literary.
悲しみをこらえきれずに、泣き出した。
Unable to hold back the sadness, she burst into tears involuntarily.
Literally 'without knowing,' implies an unconscious or gradual involuntary change. Often used for emotional shifts or habits.
For bodily functions like shivering, sweating, or heart racing that the conscious mind doesn't control.
Means 'naturally' or 'spontaneously,' often used for bodily reactions that occur without deliberate effort.
寒くて自然に体が震えた。
It was so cold my body shivered involuntarily.
Means 'by itself' or 'automatically,' used when something happens without external cause or conscious control. Can sound slightly personifying.
傷がひとりでに治った。
The wound healed involuntarily (on its own).
For formal situations describing acts done without volition, such as in court or medical reports.
Technical term meaning 'involuntary' (opposite of voluntary). Used in medical, psychological, or legal contexts. Not for everyday conversation.
不随意運動は神経系の障害によって起こることがある。
Involuntary movements can be caused by nervous system disorders.
Means 'unconscious' or 'subconscious.' Can describe involuntary actions in psychological contexts, but also used more broadly for unawareness.
思わず is for reflexive actions triggered by surprise or emotion. つい is for habitual or careless slips, often with a sense of regret. 思わず笑った (burst out laughing involuntarily) vs つい笑った (laughed despite trying not to).
不随意 is a technical term. Using it in casual speech sounds unnatural. Stick to 思わず or 反射的に for everyday involuntary actions.
フラッシュが光って、彼女は思わず目を閉じた。
She involuntarily closed her eyes when the flash went off.
足が反射的にピクッと動いた。
My leg jerked involuntarily.
知らず知らずのうちに、彼のことが好きになっていた。
Without realizing it, I had involuntarily fallen for him.
An action done involuntarily/unconsciously.