Grammar › Core Patterns
〜てしまう — “end up doing, finish completely”
Completion or regret: 宿題をしてしまいました — I went and finished my homework
て-form + しまう marks an action as fully, irreversibly complete — often with a nuance of regret, surprise, or “oops, it's done now.” In casual speech it contracts to ちゃう (or じゃう after ん/む/ぶ/ぐ verbs): 食べてしまう → 食べちゃう.
How to form it
| Pattern | Example |
|---|---|
| て-form + しまう | 忘れる → 忘れてしまいました — I ended up forgetting (regrettably) |
| Casual contraction: 〜ちゃう / 〜じゃう | 食べてしまう → 食べちゃう — ate it all up |
Example sentences
| Japanese | Reading | Meaning |
|---|---|---|
| 財布を電車に忘れてしまいました。 | さいふをでんしゃにわすれてしまいました。 saifuwodenshaniwasureteshimaimashita。 | I accidentally left my wallet on the train. |
| そのケーキ、もう食べちゃったの? | そのけーき、もうたべちゃったの? sonoke-ki、moutabechattano? | Did you already eat that cake? |
| 宿題を全部終わらせてしまいたい。 | しゅくだいをぜんぶおわらせてしまいたい。 shukudaiwozenbuowaraseteshimaitai。 | I want to get all my homework completely finished. |
🔊 Tap any Japanese sentence to hear it; kanji link to their study pages.
Watch out
しまう doesn't always mean regret — with a positive verb like 終わらせる it just emphasizes thoroughness (“finish it all the way”). Read the verb and context, not しまう alone, to know whether it's a complaint or just completeness.