てはいけない

てはいけない is used to say that something is not allowed or forbidden.

🔹 Basic Meaning

• “must not …”
• “may not …”
• “it’s not allowed to …”

🔹 When to use てはいけない

• To say something is prohibited or not permitted
• To state rules or strict instructions
• Stronger than a polite request (ないでください)
• Common in signs, rules, and warnings (N5)

🔹 Simple Examples

ここでタバコを吸ってはいけません。
→ You must not smoke here.

入ってはいけません。
→ You may not enter.

写真を撮ってはいけません。
→ You must not take pictures.

遅れてはいけません。
→ You must not be late.

🔹 Difference (N5-friendly)

てはいけない is a strong prohibition, while ないでください is a polite request.

⭐ The Grammar Summary

• てはいけない = “must not / not allowed”
• Used with the て-form of verbs
• Expresses prohibition or rules (N5)