GrammarJLPT N5
→ to finish
Completion or Regret (Auxiliary Verb Use)
JLPT N5Auxiliary verbNeutral
When used as an auxiliary verb after the て-form of another verb, しまう adds the nuance that an action has been carried through to completion — often with an emotional overtone of regret, disappointment, or the sense that the result is irreversible. In its completion sense, しまう emphasizes that something is entirely done or finished, leaving no room to undo it. In its regret sense, it conveys that something unfortunate or unintended happened. Context determines which nuance is primary, and sometimes both overlap. In casual speech, てしまう frequently contracts to ちゃう (after て) or じゃう (after で), which learners should recognize. As a standalone main verb, しまう means "to put away" or "to store," but its auxiliary usage is far more common in everyday grammar study. It is distinct from ておく, which implies doing something in advance or leaving something in a certain state, whereas しまう focuses on finality or unintended consequences.
Functions
#1 Expressing completion of an action
Structure
Verb (て-form) + しまう
この本をもう読んでしまいました。
Here しまう is used in its past-polite form しまいました to stress that the action of reading the book has been completed entirely. The speaker is not expressing regret but rather emphasizing thoroughness — the book is completely finished. The adverb もう (already) reinforces this sense of full completion. This is the most straightforward use of しまう: the action is done and there is nothing left to do.I've already finished reading this book.
Structures
- Auxiliary verb (with て-form)
- Verb (て-form) + しまう
Common mistakes
A common mistake is using しまう with the dictionary form of a verb instead of the て-form; for example, saying 食べるしまう instead of the correct 食べてしまう. Another frequent error is failing to recognize the casual contractions ちゃう and じゃう as forms of しまう, leading to confusion in listening comprehension. Learners also sometimes overuse しまう for simple past actions where no sense of completion or regret is intended, making their speech sound overly dramatic. Finally, some learners confuse しまう with ておく: remember that ておく means doing something in preparation or leaving something as-is, while しまう emphasizes that an action is fully done or happened regrettably.
Related
てしまうちゃう・じゃうてあるておくた (past tense)てくる