てしまう / ちゃう

てしまう / ちゃう means finish completely; do accidentally. It is a JLPT N4 Japanese grammar pattern used to express that an action was completed, often with a sense of regret, accident, or thoroughness.

しまう is the standard form, while ちゃう is the casual spoken contraction. You will hear both in daily conversation and see てしまう in writing and polite speech.

What does てしまう / ちゃう mean?

Use てしまう / ちゃう when you want to express that an action was carried out fully, happened by accident, or produced a regrettable result.

Natural translations include:

• finish completely
• do something accidentally
• end up doing

The best choice depends on context. If the speaker simply completed a task, “finish completely” fits. If the result was unintentional, “do accidentally” or “end up doing” is more natural.

How to form てしまう / ちゃう

Examples of the pattern:

• やってしまう
• 食べちゃう
• 忘れてしまいました

The verb must be in the て-form before attaching しまう or ちゃう. In test questions, distractors often attach the auxiliary to the wrong stem.

When is てしまう / ちゃう used?

Use てしまう / ちゃう in situations like:

• expressing that an action is fully completed
• describing an accident or unintended result
• adding a feeling of regret or resignation
• softening or sharpening tone depending on whether you use しまう or ちゃう

Tone and register:

• てしまう is neutral and fits polite, written, and spoken Japanese
• ちゃう is casual and appears mainly in spoken Japanese among friends and family
• Both are common in JLPT N4 reading and listening materials

てしまう / ちゃう example sentences

After reading each sentence, ask whether てしまう / ちゃう signals completion, accident, or regret. That question makes the grammar easier to remember than a one-word translation.

Nuance of てしまう / ちゃう

The key nuance is that the action is done thoroughly or irreversibly, and the speaker often feels something about the result.

This matters because てしまう is not simply “finish.” It can imply:

• relief that a task is done
• regret that something happened
• resignation about an unintended outcome

ちゃう packs the same nuance into casual speech. Because it is contracted and colloquial, it can sound playful, embarrassed, or lightly frustrated depending on intonation. Read the whole sentence before choosing an English translation.

てしまう / ちゃう vs ちゃう

The two forms share the same core meaning but differ in register.

てしまう:

• standard, neutral form
• used in polite speech, essays, and formal contexts
• example: 宿題しゅくだいを全部ぜんぶやってしまいました。

ちゃう:

• casual spoken contraction
• used with friends, family, and in informal writing
• example: ケーキを全部ぜんぶ食べちゃった。

If you are speaking to a teacher or writing a report, use てしまう. If you are chatting with a close friend, ちゃう is natural.

Common mistakes with てしまう / ちゃう

A helpful practice method is to write one sentence with てしまう, then rewrite it with ちゃう and notice how the tone shifts.

Is てしまう / ちゃう on the JLPT?

Yes. てしまう / ちゃう is commonly taught as JLPT N4 grammar.

For test preparation, study the grammar point in full sentences. JLPT questions often test whether you understand the surrounding context, not just the dictionary meaning.

Practice questions for てしまう / ちゃう

Keep your first sentences simple. Once the structure feels natural, add more context so the nuance becomes clear.

Learning path for てしまう / ちゃう

To learn てしまう / ちゃう efficiently, start with its formation, then compare registers, and finally practice in context.

Related grammar to review next

• 終わる — neutral completion without the emotional weight of てしまう
• ておく — preparation done in advance
• てみる — trying something out

Browse more lessons here:

• All grammar lessons
• JLPT N4 grammar lessons

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