Meaning & Usage
✨ Basic Meaning
Expresses that something happened immediately or simultaneously with the completion of a preceding action.
🎯 Primary Function
To indicate a sudden, often unexpected, event or change occurring the moment another action is completed.
📋 Grammar Structure
Verb た-form + とたん（に）
🎭 Usage Contexts
Formal Situations
Can be used in relatively formal narration or reporting of events.
Informal Situations
Commonly used in everyday conversation to describe surprising or abrupt occurrences.
Written Language
Frequently seen in narratives, news reports, and descriptive writing.
Spoken Language
Used to add dramatic effect or emphasize the immediacy of an event.
💡 Common Applications
Describing sudden changes in weather or environment.
Use when a change happens immediately after an action.
Example: 外に出たとたん、雨が降り始めた。 (Soto ni deta totan, ame ga furihajimeta.) – The moment I stepped outside, it started raining.
Reporting surprising reactions or results.
Use when the result of an action was immediate and perhaps unexpected.
Example: 彼女は私の顔を見た途端、泣き出した。(Kanojo wa watashi no kao o mita totan, nakidashita.) – The moment she saw my face, she started crying.
Narrating quick, sequential actions in stories or reports.
Use to show one action quickly followed another.
Example: ベルが鳴ったとたん、生徒たちは一斉に立ち上がった。(Beru ga natta totan, seito-tachi wa issei ni tachiagatta.) – The moment the bell rang, the students all stood up at once.
Frequency
Moderately frequent in spoken and written Japanese, particularly when emphasizing suddenness.
Difficulty
Intermediate to Advanced (N3-N2). Understanding the nuance of suddenness and difference from similar patterns is key.
Example Sentences
ドアを開けたとたん、猫が飛び出していった。
The moment I opened the door, the cat jumped out.
彼が部屋に入ったとたん、みんなが静かになった。
The moment he entered the room, everyone became quiet.
スマホを見た途端、新しいメッセージが何件も届いていた。
The moment I looked at my smartphone, several new messages had arrived.
Notes & Nuances
📌 Important Points
Immediate Sequence
～たとたん（に） strongly emphasizes that the second event happens immediately after the first, with almost no time gap.
Example: 走り出したとたん、靴ひもがほどけた。(Hashiridashita totan, kutsuhimo ga hodoketa.) – The moment I started running, my shoelace came undone.
Unexpected/Observed Event
The second event is typically something sudden, unexpected, or observed by the speaker, rather than a planned action or a natural, expected consequence.
Example: 電気を消したとたん、部屋が真っ暗になった。(Denki o keshita totan, heya ga makkura ni natta.) – The moment I turned off the light, the room went completely dark. (A simple, observed consequence.)
⚠️ Common Mistakes
❌ Using non-た form
✅ Always use the た-form of the verb.
The structure requires the completed action form (た-form) to indicate the immediate follow-up.
❌ Using volitional/intentional second clause
✅ The second clause should describe an event, state, or action that is observed, not willed by the speaker.
～たとたん describes a reaction or consequence, not a planned action.
🏛️ Cultural Context
Politeness Level: Neutral.
Social Situations: Appropriate in most social contexts, depends on the overall sentence structure and vocabulary.
Regional Variations: No significant regional variations in the use of this pattern.
🔍 Subtle Differences
～たとたん（に） vs. ～すると
～たとたん（に） emphasizes the instant, often surprising, nature of the second event. ～すると is more general and simply indicates a sequence of events, without strong emphasis on immediacy or surprise.
When to use: Use ～たとたん（に） when you want to highlight the suddenness and minimal time gap. Use ～すると for a neutral sequential relationship.
～たとたん（に） vs. ～かと思うと/かと思ったら
Both imply suddenness, but ～かと思うと/かと思ったら can sometimes imply a slightly longer pause or a change/contrast that is particularly unexpected or perhaps slightly confusing. ～たとたん（に） is purely about instantaneous sequence.
When to use: Use ～たとたん（に） for strict, immediate consequence. Use ～かと思うと/かと思ったら when the suddenness or contrast is particularly striking or confusing.
～たとたん（に） vs. ～次第
～次第 (しだい) typically means “as soon as” in the sense of future action based on a trigger, often used in formal contexts for announcements or promises. ～たとたん（に） describes a sudden event that happened immediately after something in the past or present.
When to use: Use ～たとたん（に） to describe something that just happened suddenly. Use ～次第 to promise or announce an action you will take immediately after something happens in the future.
📝 Conjugation Notes
Connects directly to the た-form of a verb.
🔊 Pronunciation Tips
「とたん」 is pronounced like a single word. The に is often optional and can be omitted.
🧠 Memory Tips
Think of 「とたん」 (totan) as a sound effect like a sudden “pop” or “snap” that happens the instant something is finished (た form). Imagine the action finishes (た form) and *pop!* the next thing happens.
Practice Exercises
部屋の電気を（ ）、赤ちゃんが泣き出した。
つけたとたん
つけているとたん
つくるとたん
つけようとたん
暑かったのに、山の頂上に（ ）、急に寒くなった。
つくとたん
ついたとたん
つきるとたん
つこうとたん
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