JLPT N4ComparisonUpdated 2026-09-25

〜ておく vs 〜てしまう te oku · te shimau

〜ておく means to do something in advance or leave it in a state; 〜てしまう marks completion or an unintended outcome. 予約しておく highlights preparation for later. 予約してしまう focuses on the action being done, with regret possible if the context calls for it. てしまう by itself does not mean “accidentally”; context determines whether completion feels welcome or unfortunate.

also written とく / ちゃう / じゃう

do it in advance · finish it off · do it by accident

Sentences

6 sentences, word by word

ておく — ready for later

polite

。

Hover, tap, or tab through the words.

ビール

ビール［1］

beer

noun · from Dutch bier, not English

Ask Rikai

を

marks the direct object

particle · pronounced お

Ask Rikai

冷やして

ひやして

chill; cool

て-form of 冷やす · transitive; 冷える is what happens on its own

Ask Rikai

おきます

and leave it that way

polite of おく · from 置く, “to put down”

〜ておくN4do in advance

Ask Rikai

I'll put the beer in to chill.

ておく — a request to prepare

polite

。

Hover, tap, or tab through the words.

会議

かいぎ［1］

meeting; conference

noun · 会議をする is the verb form

Ask Rikai

の

links noun to noun

particle · A の B = B belonging to A

Ask Rikai

前

まえ［1］

before; in front of

noun · 〜の前に is how you say “before something”

Ask Rikai

に

at (a point in time)

particle · 前 needs it to mean “before”

Ask Rikai

資料

しりょう［1］

documents; materials

noun · the standard word for meeting handouts

Ask Rikai

を

marks the direct object

particle · pronounced お

Ask Rikai

読んで

よんで

read

て-form of 読む · む verbs take んで

Ask Rikai

おいて

have it done beforehand

て-form of おく · this is the request version of ておきます

〜ておくN4do in advance

Ask Rikai

ください

please (do)

polite request · from くださる

Ask Rikai

Please read the documents before the meeting.

てしまう — done, all of it

polite

。

Hover, tap, or tab through the words.

宿題

しゅくだい［0］

homework

noun · 宿 lodging + 題 topic

Ask Rikai

は

as for — the topic

particle · written は, read わ

Ask Rikai

もう

もう［1］

already

adverb · this is the word that makes it completion, not regret

Ask Rikai

やって

て-form of やる · the everyday twin of する

Ask Rikai

しまいました

finished it off

polite past of しまう · completion here, not regret

〜てしまうN4finish completely

Ask Rikai

I've already finished the homework.

てしまう — and you can't take it back

plain

。

Hover, tap, or tab through the words.

財布

さいふ［0］

wallet; purse

noun · 財 wealth + 布 cloth

Ask Rikai

を

marks the direct object

particle · pronounced お

Ask Rikai

電車

でんしゃ［0］

train

noun · 電 electric + 車 vehicle

Ask Rikai

に

on; in

particle · where the thing ended up, not where you were

Ask Rikai

忘れて

わすれて

forget; leave behind

て-form of 忘れる · covers both forgetting and leaving things behind

Ask Rikai

しまった

and I wish I hadn't

plain past of しまう · regret, and it's already done

〜てしまうN4did it, unfortunately

Ask Rikai

I went and left my wallet on the train.

ておく — leave it as it is

polite

。

Hover, tap, or tab through the words.

窓

まど［1］

window

noun · 窓を開ける is the standard pair

Ask Rikai

は

as for — and only this

particle · picks the window out from everything else in the room

Ask Rikai

開けて

あけて

open

て-form of 開ける · transitive; 開く opens by itself

Ask Rikai

おいて

and leave it that way

て-form of おく · “leave as is” here, not “prepare”

〜ておくN4leave it as it is

Ask Rikai

も

even

particle · part of てもいい, “it's fine even if”

Ask Rikai

いい

good; fine

i-adjective · irregular — the past is よかった

Ask Rikai

です

polite copula · closes the question politely

Ask Rikai

か

question marker

particle · turns the sentence into a question

Ask Rikai

Is it alright if I leave the window open?

the casual てしまう

casual

。

Hover, tap, or tab through the words.

ケーキ

ケーキ［1］

cake

noun · from English

Ask Rikai

を

marks the direct object

particle · pronounced お

Ask Rikai

全部

ぜんぶ［1］

all of it

noun used adverbially · no particle needed

Ask Rikai

食べちゃった

たべちゃった

ate the lot — oops

食べてしまった, contracted · てしまう becomes ちゃう in speech

〜ちゃうN4casual てしまう

Ask Rikai

I ate the whole cake.

Structure

How do you form 〜ておく and 〜てしまう?

Verb［て］＋おく

買っておく. From 置く, “to put”: do it and leave it there, ready for when it's needed.

Verb［て］＋しまう

読んでしまった. All the way to the end, nothing left over. Often alongside もう or 全部.

Verb［て］＋しまう

忘れてしまった. Identical form — context alone decides. Something you didn't mean to do and can't take back.

〜ておく → 〜とく／〜てしまう → 〜ちゃう

買っとく, 忘れちゃった. What people actually say. でしまう becomes じゃう: 飲んじゃった.

Meaning

What's the difference between 〜ておく and 〜てしまう?

Both were ordinary verbs once, and both still carry their old meaning. 置く is “to put something down”; しまう is “to put something away, to finish with it.” Everything the grammar does follows from that.

ておく is preparation. ビールを冷やしておきます — chill the beer and leave it chilled, because people are coming later. English usually drops this entirely, which is why learners under-use it: 予約する and 予約しておく both come out as “make a reservation”, but only the second one says the point of it is later.

Its second sense is “leave it as it is”: 窓は開けておいてもいいですか — can I leave the window open? Still the same 置く: put it there, don't touch it.

てしまう is the end of the line. Half the time that's an achievement — 宿題はもうやってしまいました, done, all of it. The other half it's a mistake you can't take back: 財布を電車に忘れてしまった. Nothing in the grammar separates the two. The adverbs do: もう and 全部 point at completion; うっかり and つい point at regret.

Watch out

Where does this go wrong?

Hearing てしまう as regret every time

Half the time it just means finished. 全部読んでしまった is an achievement, not a confession. The clue is usually the adverb: もう and 全部 point at completion, うっかり and つい at regret.

Leaving ておく off because English does

予約する and 予約しておく both translate as “make a reservation”. Dropping ておく isn't ungrammatical, but it loses the reason you're doing it now rather than later — which is often the whole point of the sentence.

ちゃう and じゃう

Which one you get depends on the て-form. て → ちゃう: 食べて→食べちゃう. で → じゃう: 飲んで→飲んじゃう. Same split for とく and どく.

Also asked

Questions people ask about ておく and てしまう

Does ておく always mean “in advance”?

Not quite. The second sense is “leave it as it is”: そのままにしておいて, “just leave it.” Both come from 置く — put it there and don't touch it.

How do I tell completion from regret in てしまう?

Context, and usually an adverb. もう and 全部 point at completion; うっかり, つい and any bad news point at regret. Nothing in the grammar itself distinguishes them.

What is 〜とく?

The contracted ておく. 買っておく becomes 買っとく, 読んでおく becomes 読んどく. Speech only — never write it in anything formal.

Can I use ておく with a verb I don't control?

No. ておく is deliberate preparation, so the verb has to be something you choose to do. 雨が降っておく is meaningless.

Is しまった on its own rude?

It's the mild one. しまった！ is roughly “damn” or “oh no” — a mistake you've just noticed. Perfectly usable in front of most people.

Can ておく and てしまう combine?

Not stacked, but they trade places for the same job. 書いておく is writing it now for later; 書いてしまう is getting it written and off your plate. Both are common answers to “when will you do it?”

References