JLPT N1・N3 Grammar – Difference between “〜とたん” and “〜と思いきや”

Table of Contents

1. Difference between “〜とたん” and “〜と思おもいきや”
2. Aとたん(に)B
3. Aと思おもいきやB
4. Let’s Compare
5. Summary
6. Quiz
7. Similar Articles
8. Comment

Q: What is the difference between “〜とたん” and “〜と思おもいきや”?

A: Both expressions describe a situation where one event occurs right after another. However, “〜とたん” emphasizes the immediate timing and sequence, while “〜と思おもいきや” focuses on unexpected outcomes or results contrary to expectation. Their nuances and usage are clearly different.

AとたんB (JLPT N3)

[Meaning]
This expression indicates that something happens immediately at the moment a certain action or event occurs. It is often used to describe unexpected events or sudden changes.

[Rule]
[V] Verb past form + とたん（に）

[Examples]
ドアを開あけたとたん、強つよい風かぜが入はいってきました。
I opened the door, and a strong wind rushed in at that very moment.

外そとに出でたとたん、雨あめが降ふってきました。
As soon as I stepped outside, it started to rain.

子供こどもは母親ははおやの顔かおを見みたとたん、泣なき出だしました。
The child burst into tears the moment he saw his mother’s face.

This expression indicates that B happens immediately after A ends, almost at the same time.
B is often an unexpected event or sudden change for the speaker, and the key points are the temporal sequence and the meaningful connection between A and B.

[Examples]
騒さわがしかった教室きょうしつが、先生せんせいが来きたとたんに静しずかになりました。
The noisy classroom suddenly became quiet the moment the teacher walked in.
⇒ A “The teacher walked in” and B “The classroom became quiet” occurred in immediate succession, showing a cause-and-effect relationship.

立ち上た　あがったとたん、めまいがしました。
The moment I stood up, I felt dizzy.
⇒ A “I stood up” was immediately followed by B “I felt dizzy,” an unexpected physical change.

真まっ暗くらになったとたん、会場かいじょうには歓声かんせいが響ひびき渡わたりました。
The moment it went completely dark, cheers echoed through the hall.
⇒ A “It went completely dark” was followed instantly by B “cheers echoed,” showing a strong sense of timing and reaction.

Aと思おもいきやB (JLPT N1)

[Meaning]

① You thought something would happen, but the result turned out to be the opposite of what you expected

② Right after something happened, the opposite occurred immediately afterward
*In both cases, the expression conveys a sense of surprise or something unexpected.

[Rule]

[V] Verb plain form + と + 思おもいきや

[A] い adjective plain form + と + 思おもいきや

[Na] な adjective plain form + と + 思おもいきや

[N] Noun plain form + と + 思おもいきや

[Examples]
父ちちは反対はんたいすると思おもいきや、賛成さんせいしてくれました。（①）
My father, whom I expected to oppose my decision, surprisingly agreed with it.

彼女かのじょは静しずかな人ひとだと思おもいきや、とてもおしゃべりでした。（①）
I thought she was a quiet person, but it turned out she was very talkative.

雨あめがやんだかと思おもいきや、また降ふり出だしました。（②）
Just when I thought the rain had stopped, it started coming down again.

弟おとうとは帰かえってきたと思おもいきや、またすぐに出でかけました。（②）
I thought my younger brother had come home, but he went out again right away.

This expression has two main uses.
The first is when something unexpected (B) happens immediately after A, contrary to what the speaker had anticipated.
In this case, it carries the nuance of “I thought A would happen, but actually, it didn’t.”

The second is when A happens, but instead of continuing, it is quickly followed by B, which is the opposite of A.
This emphasizes the speaker’s surprise that “just as I thought A was happening, the opposite happened right away.”

In both cases, the expression strongly conveys the speaker’s sense of surprise or the feeling that things turned out differently than expected.

[Examples]
父ちちに留学りゅうがくしたい意志いしを伝つたえたら、反対はんたいすると思おもいきや大だい賛成さんせいでした。（①）
When I told my father that I wanted to study abroad, I thought he would oppose the idea, but to my surprise, he was completely in favor of it.
⇒ A “I thought my father would oppose it,” but B “he agreed” — this expresses an unexpected outcome.

子供こどもたちは静しずかになったかと思おもいきや、また騒さわぎ始はじめました。（②）
The children had just become quiet, or so I thought — but then they started making noise again.
⇒ A “They became quiet” was immediately followed by B “They started making noise again,” showing an unexpected turn of events.

Let’s Compare

Which expression is appropriate in the following sentence?

[Examples]
① 夏なつが来きたとたん、涼すずしくなりました。
② 夏なつが来きたと思おもいきや、涼すずしくなりました。

⇒ The correct answer is ②.
Generally, we expect it to become hot when summer comes, so the fact that it became cool instead is an unexpected result.
Therefore, “〜と思おもいきや” is the more appropriate expression.

[Examples]
① 寝ねたとたん、大おおきな雷かみなりが鳴なりました。
② 寝ねたと思おもいきや、大おおきな雷かみなりが鳴なりました。

⇒ The correct answer is ①.
Since B “the thunder struck” happened immediately after A “I fell asleep,” showing a clear time sequence, “〜とたん” is the appropriate expression.

Summary

[Aとたん（に）B]

• It indicates that B happens immediately after A ends, almost at the same time.
• B is often an unexpected event or a sudden change.
• The key is the temporal sequence and the meaningful connection between A and B.

[Aと思おもいきやB]

• ① Used when something unexpected (B) happens right after A, from the speaker’s point of view.
• It conveys the meaning: “I thought it would be A, but in reality, it was not.”
• ② Expresses surprise when A happens but is immediately followed by B, which is the opposite of A.
• It is used when the speaker expected A to continue, but it was suddenly reversed.
• In both ① and ②, the expression strongly reflects the speaker’s feelings of surprise or the unexpected nature of the situation.

Quiz

Read the following sentence and choose the expression that fits the context from the options provided in the parentheses.

Click on the question to check the answer.

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