Meaning & Usage
✨ Basic Meaning
Expresses that immediately after something happens, something else happens.
🎯 Primary Function
To describe a rapid succession of events or a sudden, often unexpected, change in situation or action.
📋 Grammar Structure
Verb (た form) + かと思うと / かと思ったら
Noun + だ + った + かと思うと / かと思ったら (Less common, use だと思ったらかと思ったら instead)
い-Adjective + かった + かと思うと / かと思ったら (Less common, use かったと思ったら instead)
な-Adjective + だ + った + かと思うと / かと思ったら (Less common, use だと思ったらかと思ったら instead) Most commonly connected to the plain past (た) form of a verb describing the first action/state.
🎭 Usage Contexts
Formal Situations
Usable, but more common in slightly less formal or narrative contexts.
Informal Situations
Commonly used in everyday conversation and descriptions.
Written Language
Frequently seen in novels, essays, and descriptions of dynamic scenes.
Spoken Language
Very common in spoken Japanese when describing quick sequences of events.
💡 Common Applications
Describing a person’s rapidly changing mood or behavior.
Used when someone’s feelings or actions shift quickly from one state to another.
Example: 彼はさっきまで笑っていたかと思うと、急に泣き出した。 (Kare wa sakki made waratte ita ka to omou to, kyū ni nakidashita. – Just when I thought he was laughing, he suddenly started crying.)
Describing a quick sequence of actions by one person or object.
Used to show a series of events happening one right after the other with little or no pause.
Example: 子供は部屋に入ってきたかと思ったら、もうおもちゃを散らかしていた。(Kodomo wa heya ni haitte kita ka to omottara, mō omocha o chirakashite ita. – Just when I thought the child had entered the room, they were already scattering toys around.)
Describing sudden changes in the environment or situation.
Used for natural phenomena or situations that change rapidly.
Example: 晴れていたかと思うと、大粒の雨が降ってきた。(Harete ita ka to omou to, ōtsubu no ame ga futte kita. – Just when I thought it was sunny, large drops of rain started falling.)
Frequency
Moderately frequent among native speakers, particularly in descriptive contexts.
Difficulty
Intermediate to Advanced (N3-N2). Understanding the nuance of “sudden/rapid succession” is key.
Example Sentences
赤ちゃんは眠ったかと思うと、すぐ泣き始めた。
Just when I thought the baby had fallen asleep, it immediately started crying.
空が暗くなったかと思ったら、雷が鳴り出した。
Just when I thought the sky had gotten dark, thunder started rumbling.
彼は席に着いたかと思うと、もう立ち上がって出て行った。
Just when I thought he had taken a seat, he already stood up and left.
Notes & Nuances
📌 Important Points
Emphasis on rapid succession or sudden change.
The pattern highlights that the second event happens immediately or very quickly after the first, often unexpectedly.
Example: 電車が止まったかと思うと、ドアが開いた。(Densha ga tomatta ka to omou to, doa ga aita. – Just when the train stopped, the doors opened. – Implies the action happened instantly after stopping.)
Often describes unpredictable or dynamic situations.
It’s frequently used to describe situations where things change quickly and without much predictability.
Example: 彼の気分は変わりやすい。嬉しそうだったかと思ったら、次の瞬間には怒っている。(Kare no kibun wa kawariyasui. Ureshisō datta ka to omottara, tsugi no shunkan ni wa okotte iru. – His mood changes easily. Just when you think he looked happy, the next moment he’s angry.)
⚠️ Common Mistakes
❌ Using it for actions that happen sequentially but not immediately.
✅ Use connectors like ～てから or ～と instead for simple sequences.
This pattern specifically emphasizes the *immediacy* and sometimes *unexpectedness* of the second event following the first.
❌ Incorrect conjugation, especially with non-verbs.
✅ Mostly connect to the plain past (た) form of verbs. For adjectives/nouns, it’s less common and often restructured (e.g., ～だと思ったら or state+かと思ったら).
The standard and most frequent connection is Verb-た form.
🏛️ Cultural Context
Politeness Level: Neutral. It’s not specifically polite or impolite.
Social Situations: Used in various social situations for narration or description of events.
Regional Variations: Standard Japanese, no significant regional variations in this pattern.
🔍 Subtle Differences
～（か）と思うと/～（か）と思ったら vs. ～たとたんに
Both express something happening immediately after. ～たとたんに emphasizes the *moment* the first action finishes and the second begins. ～（か）と思うと/～（か）と思ったら focuses more on the *unexpectedness* or *rapid succession* from the perspective of the observer.
When to use: Use ～たとたんに for strict immediacy at the moment of completion. Use ～（か）と思うと/～（か）と思ったら when highlighting the quick shift or unpredictable nature of the sequence.
～（か）と思うと/～（か）と思ったら vs. ～か～ないかのうちに
～か～ないかのうちに emphasizes that the second action happens almost *before* the first action is even finished or completed.
When to use: Use ～か～ないかのうちに when the overlap is very strong, almost simultaneous. Use ～（か）と思うと/～（か）と思ったら for events that happen immediately *after* the first, highlighting the speed/shift.
～（か）と思うと/～（か）と思ったら vs. ～ているうちに
～ているうちに means “while something is happening,” describing an action that occurs *during* an ongoing state or action. ～（か）と思うと/～（か）と思ったら describes something happening *immediately after* the first event concludes (or seems to conclude).
When to use: Use ～ているうちに for concurrent actions/states. Use ～（か）と思うと/～（か）と思ったら for sequential, rapid actions.
📝 Conjugation Notes
The most common and standard connection is with the plain past tense (た form) of verbs. While theoretical connections exist for other forms/parts of speech (like Noun/Adj + だった/か
🔊 Pronunciation Tips
Pronounce と思うと and と思ったら naturally, linking the particle か smoothly to the verb form.
🧠 Memory Tips
Think of “かと思うと” as “just when you thought X happened…” followed immediately by Y. The “思う” part hints at the perspective or perception of the sudden change.
Practice Exercises
子供は遊んでいた（ ）、急に眠ってしまった。
かと思うと
ているうちに
たとたんに
にあたって
彼は部屋に入った（ ）、すぐに出て行った。
ところに
たとえ
かと思ったら
わけにはいかない
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