Video
Let’s watch this short video for a quick overview.
Source: gokigen japanese official YouTube Channel
Introduction
Want to say things like:
- “You must not smoke.”
- “You must not talk in the library.”
- “You must not forget your homework.”
In Japanese, the expression 〜てはいけません is used to clearly prohibit actions. Whether you’re reading a sign in Japan or giving a rule to someone, this is the go-to grammar point for saying “Don’t do that!”
Let’s learn how to use this powerful and polite form of prohibition in Japanese.
1. What Does 〜てはいけません Mean?
V-てはいけません means:
- You must not do 〜
- It is not allowed to 〜
- Don’t do 〜 (polite)
It combines the て-form of a verb with はいけません, which literally means “you can’t go on (doing something)” — but in actual use, it functions as “you must not”.
2. How to Form the Sentence
The structure is simple:
Verb (in て-form) + はいけません
Example Conjugations
| Verb | て-form | Final Sentence | Meaning |
|---|---|---|---|
| 寝（ね）る | 寝て | 寝てはいけません | You must not sleep |
| 話（はな）す | 話して | 話してはいけません | You must not talk |
| 飲（の）む | 飲んで | 飲んではいけません | You must not drink |
| 忘（わす）れる | 忘れて | 忘れてはいけません | You must not forget |
| 開ける | 開けて | 開けてはいけません | You must not open |
3. When to Use This Grammar
Use 〜てはいけません when:
- You want to prohibit an action
- You’re talking about school, work, or public rules
- You need to be polite but clear
It’s commonly found on signs, in instructions, and in classroom settings.
4. Real-Life Examples
| Japanese | English |
|---|---|
| 学校（がっこう）で寝（ね）てはいけません。 | You must not sleep at school. |
| お酒（さけ）を飲（の）んではいけません。 | You must not drink alcohol. |
| ドアを開（あ）けてはいけません。 | You must not open the door. |
| 宿題（しゅくだい）を忘（わす）れてはいけません。 | You must not forget your homework. |
| 自転車（じてんしゃ）に乗（の）ってはいけません。 | You must not ride a bicycle. |
5. Practice: Can You Say It?
Convert the following into 〜てはいけません form:
- 座る（すわる）→ 座ってはいけません
- 話す（はなす）→ 話してはいけません
- 休む（やすむ）→ 休んではいけません
- 忘れる（わすれる）→ 忘れてはいけません
- 開ける（あける）→ 開けてはいけません
- ゲームをする → ゲームをしてはいけません
6. Asking and Answering with 〜てはいけません
You can answer questions about permission like this:
| Question | Answer |
|---|---|
| 学校でゲームをしてもいいですか？ Is it okay to play games at school? | いいえ、してはいけません。 No, you must not do that. |
| 図書館（としょかん）で話（はな）してもいいですか？ Is it okay to talk in the library? | いいえ、話してはいけません。 No, you must not talk. |
| 子（こ）どもはお酒（さけ）を飲（の）んでもいいですか？ Is it okay for children to drink alcohol? | いいえ、飲んではいけません。 No, they must not drink (it). |
7. FAQ – Frequently Asked Questions
- QWhat’s the casual version?
- A
- 〜ちゃダメ
Example: そのクッキーは食（た）べちゃダメだよ！ / Don’t eat those cookies! - 〜じゃダメ
Example: 未成年（みせいねん）はお酒（さけ）を飲（の）んじゃダメ！ / Minors should not drink alcohol!
- 〜ちゃダメ
- QHow strong is the prohibition with “~te wa ikemasen”? How does it differ from other prohibition expressions like “~naide kudasai”?
- A
“~te wa ikemasen” expresses a relatively clear “prohibition,” often used for rules, regulations, or by a superior towards a subordinate. It clearly conveys something one must not do. On the other hand, “~naide kudasai” takes the form of a request, “Please stop doing ~” or “Please don’t do ~,” carrying a nuance of a more polite and milder prohibition or request.
- QAlthough “~te wa ikemasen” is a polite expression, can it sometimes give a strict impression?
- A
Although it uses the polite form (desu/masu style), because it directly conveys prohibition, it can potentially sound a bit strict or cold depending on the situation and the listener. It should especially be avoided when speaking to someone of equal or higher status. In situations requiring more consideration, using softer expressions like “~naide itadakemasu ka” (Could I possibly ask you not to do ~?) or “~ wa go-enryo kudasai” (Please refrain from ~) might be more appropriate.
- QWhat’s the opposite of 〜てはいけません？
- A
It’s 〜てもいいです, which means “It’s okay to do 〜.”
Example:
→ 写真を撮ってもいいです。 = You may take a picture.
Conclusion
Now you can say what is not allowed in Japanese!
✅ Use 〜てはいけません to express prohibition
✅ Master the て-form of verbs to build correct sentences
✅ Be clear and polite when giving rules or instructions
🎯 Try writing 3 classroom rules using this pattern!
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