Saying one must not perform an action is conveyed by a verb in its て form, the particle は, and the adjective だめ (“cannot”, “must not”, “not allowed”), ending in だ.

Examples of ～てはだめだ

See Also

• To discourage (rather than prohibit) an action, ～てはいけない is used.

Further Reading

• Chino, Naoko. “Commands and Prohibitions.” Japanese Verbs at a Glance, Kodansha, 2000, pp. 35–36
• Chino, Naoko. “Basic Pattern 27.” A Dictionary of Basic Japanese Sentence Patterns, Kodansha, 2000, pp. 193–194
• Kamiya, Taeko. “Commands, Requests, Suggestions, Approval, Disapproval, Prohibition, and Obligation.” Japanese Sentence Patterns for Effective Communication, Kodansha, 2005, p. 175