When learning Japanese, it’s important not only to know how to ask questions and make requests but also how to express rules and prohibitions. One of the most common ways to say “You must not…” or “It’s not allowed…” in Japanese is by using:

〜てはいけません

Let’s take a closer look at what it means, how to use it, and when it’s appropriate.

📘 What does 〜てはいけません mean?

The phrase 〜てはいけません literally translates to “you must not do…” or “you are not allowed to do…”. It’s a formal and polite way to prohibit an action.

It can be used in various contexts—such as schools, workplaces, public areas, or even in conversations when you’re telling someone gently but firmly what’s not acceptable.

🛠️ How to Form 〜てはいけません

To form this expression, you need the te-form of a verb followed by はいけません.

Formula:
Verb (て-form) + はいけません

Let’s look at some examples:

👀 Variations and Casual Forms

In casual conversation, especially among friends or family, you might hear:

• 〜ちゃだめ (more casual)
• 〜じゃだめ (used with で-form verbs)

Examples:

• ここで飲のんじゃだめ！(You can’t drink here!)
• ゲームしちゃだめ！(Don’t play games!)

These are less formal and commonly used with children or close friends.

✅ Practice: Can You Translate These?

Try translating these into Japanese using 〜てはいけません:

1. You must not smoke here.
2. Don’t use your phone in class.
3. You must not park the car there.

🗣️ Cultural Tip

In Japan, following rules and social norms is very important, and you’ll often see signs in public places that use 〜てはいけません. For example:

• 「たばこを吸すってはいけません」(No smoking)
• 「ごみを捨すててはいけません」(Do not litter)
• 「触さわってはいけません」(Do not touch)

Being aware of these expressions not only helps you stay out of trouble but also shows respect for local customs.

✨ Summary

• 〜てはいけません is used to express prohibition politely.
• It’s made by attaching はいけません to the te-form of a verb.
• There are more casual versions like 〜ちゃだめ.
• Knowing this grammar helps you understand rules and behave appropriately in Japanese society.

Why not look around you and try to write a few “You must not…” sentences in Japanese? Practice makes perfect!

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