〜てしまう: Completion and Regret ('Ended Up') Explained
The finality it lays on the verb
〜てしまう takes a plain action and colors it. One color is completion: the action is carried through to the end, finished off, done entirely. The other color is regret or the unexpected: something happened that you wish hadn't, often unintentionally. Context tells you which one is meant — and sometimes both shades are present at once. Because regret and accidents are usually things that already happened, you'll meet the past form 〜てしまった constantly.
ヤッタンは本を一日で読んでしまった。
ヤッタンは ほんを いちにちで よんで しまった。
Yattan finished reading the whole book in one day.
Completion — read it all the way through.
モチは大事なメールを消してしまった。
モチは だいじな メールを けして しまった。
Mochi accidentally deleted an important email.
Regret — unintended and unfortunate.
ヤッタンの弟がケーキを全部食べてしまった。
ヤッタンの おとうとが ケーキを ぜんぶ たべて しまった。
Yattan's little brother ate the whole cake.
Can read as completion ('ate it all') or regret ('and there was none left') — context decides.
Which verbs it attaches to, and how
てしまう rides on any verb through its て-form: build the て-form, then add しまう. If that て-form ends in the voiced で, the pairing becomes でしまう. しまう itself conjugates like a normal う-verb, so you get しまう / しまった / しまいます / しまいました — and for the past you want しまった, not しまいた.
| Verb | て-form | + しまう | Meaning |
|---|---|---|---|
| やる (do) | やって | やってしまう | end up doing / finish doing |
| 忘れる (forget) | 忘れて | 忘れてしまった | (unfortunately) forgot |
| 読む (read) | 読んで | 読んでしまう | read it all / finish reading |
| 飲む (drink) | 飲んで | 飲んでしまった | drank it all up |
Notice that 読む and 飲む make a で て-form — that voicing carries straight through when the phrase contracts in casual speech. Everyday Japanese squeezes てしまう down to ちゃう and でしまう down to じゃう (past: ちゃった and じゃった), a shortening you'll meet constantly in conversation, manga, and song lyrics. The trap is the voicing: only plain て collapses to ちゃう, while で always keeps its voice into じゃう (読んで → 読んじゃう, never 読んちゃう). In polite or written situations, stay with しまいます / しまいました: 食べてしまいました.
| Form | Core idea | Example |
|---|---|---|
| てしまう → ちゃう | after the plain -te ending | 食べてしまう → 食べちゃう = end up eating |
| てしまった → ちゃった | past, after -te | 忘れてしまった → 忘れちゃった = (oops) forgot |
| でしまう → じゃう | after the voiced -de ending | 飲んでしまう → 飲んじゃう = drink it all |
| でしまった → じゃった | past, after -de | 死んでしまった → 死んじゃった = (sadly) died |
あ、ヤッタンの弟がジュースを飲んじゃった。
あ、ヤッタンの おとうとが ジュースを のんじゃった。
Oh no, Yattan's little brother drank all the juice.
飲んでしまった → 飲んじゃった (で → じゃ).
モチ、もう全部終わっちゃったよ。
モチ、もう ぜんぶ おわっちゃったよ。
Mochi, it's all finished already!
終わってしまった → 終わっちゃった (completion, casual).
Use ちゃう / じゃう with friends; keep てしまう / てしまいます for polite or written situations.
Both shades in real sentences
The completion meaning often pairs with words like 全部 ("all"), もう ("already"), or a time limit — it stresses that the job is fully done.
先生は宿題を全部チェックしてしまいました。
せんせいは しゅくだいを ぜんぶ チェックして しまいました。
The teacher finished checking all the homework.
Completion, polite.
ヤッタンは早く仕事を終わらせてしまいたい。
ヤッタンは はやく しごとを おわらせて しまいたい。
Yattan wants to just get the work finished and over with.
してしまいたい = want to get it completely done.
The regret meaning carries an "oops," "darn," or "I can't believe I did that" feeling. It's how you signal that something was a mistake, an accident, or simply unlucky.
モチは電車で寝てしまった。
モチは でんしゃで ねて しまった。
Mochi ended up falling asleep on the train.
Unintended — he didn't mean to.
ヤッタンは大切なお皿を割ってしまった。
ヤッタンは たいせつな おさらを わって しまった。
Yattan went and broke an important plate.
Regret over an accident.
Set against the plain verb
Swap 食べた for 食べてしまった and you don't change what happened — you add a stamp of finality: the action is sealed, carried to its end, beyond taking back. That extra layer is exactly why the same form can read as completion or regret; the verb alone stays neutral. Two things worth holding onto:
- It isn't always regret. 全部やってしまった can simply mean "got it all done." Let the context and words like 全部 / もう tell you which shade is in play.
- しまう here is not the verb "to put away." With a て-form it's a grammatical helper carrying finality, so don't translate it literally.
The short version
- 〜てしまう = て-form + しまう; with a で て-form it's でしまう.
- Two shades: completion (finish entirely) and regret / accident (ended up, oops) — both spring from finality.
- Past 〜てしまった is the most common form; polite is しまいました.
- Casual: てしまう → ちゃう, でしまう → じゃう, past ちゃった / じゃった.
Practice it
Choose the correct てしまう / ちゃう / じゃう form and meaning.
＿＿＿に入れるのに最もよいものを選びなさい。
Choose the grammar pattern that best completes the sentence.
ヤッタンは面白い本を一日で全部読んで＿＿＿。
Frequently asked questions
Does 〜てしまう always mean regret?
No. It has two meanings: completion (finishing something entirely, like 全部やってしまった = 'got it all done') and regret or accident (財布を忘れてしまった = 'I unfortunately forgot my wallet'). Context decides, and sometimes both shades are felt at once.
When do I use ちゃう versus じゃう?
Use ちゃう when the て-form ends in plain て (食べて → 食べちゃう). Use じゃう when it ends in the voiced で (飲んで → 飲んじゃう, 読んで → 読んじゃう). The past forms are ちゃった and じゃった.
Is てしまった really that common?
Yes. Because regret and accidents are usually about things that already happened, the past 〜てしまった (and casual 〜ちゃった) is the form you'll hear most often.
Can I use てしまう in polite speech?
Yes — just conjugate しまう politely: 食べてしまいました. The contractions ちゃう / じゃう are casual, so save them for friends and informal writing.
Where 〜てしまう fits
Shaky on this? Get these solid first
- 〜てください · N5 — 〜てください is the standard way to politely ask someone to do something ('please do…'). Learn the formation, the negative 〜ないでください, softer variations, and see clear examples.
- The て-form · N5 — The て-form is the gateway to dozens of Japanese grammar patterns. Learn the conjugation rules for every verb group, the famous song trick, and see clear examples.
Don't confuse it with
- 〜ている · N5 — 〜ている has two big jobs: an ongoing action ('is doing') and a continuing state ('is in a state'). Learn when it means which, how to form it, and see clear examples.
Hear it in a real conversation
See this pattern used naturally in a real-situation dialogue:
More N4 grammar to explore
Keep going with related patterns at the same level:
- 〜間 — 〜間 means 'the whole time while' and pairs with a continuous action; 〜間に means 'at some point during.' Learn the formation, the key difference, and a clear minimal pair.
- 〜までに — 〜までに marks a deadline: do something by a time or event — 5時までに帰る ('be back by 5'). Learn the formation and how までに differs from まで ('until').
- Volitional Form — The plain volitional form means 'let's ~' or 'I'll ~'. Learn how to make 〜よう/〜おう from every verb type, how it relates to 〜ましょう, and what it builds toward.
- 〜ようと思う — 〜ようと思う uses the volitional form + と思う to say you've decided to do something: 勉強しようと思う. Learn the formation, the 〜ようと思っている variant, and how it differs from つもり and 予定.
- 謙譲語 — 謙譲語 (kenjougo) is humble Japanese: you lower yourself and your group to honor others. Learn the お〜する pattern and special humble verbs like 参る, いたす, 申す, and 伺う.
- 〜のに — This 〜のに attaches to a dictionary-form verb to mean 'for doing X' or 'in order to X', setting up a comment about time, cost, or usefulness — 行くのに1週間かかった (it took a week to go). Not the same のに as 'even though'.