〜てはならない: 'Must Not' (Meaning + Examples)
A formal "must not"
〜てはならない states that an action is forbidden — by law, rule, morality, or social convention. It reads as more formal and weighty than everyday prohibitions.
やったんは、他人の秘密を勝手に話してはならないと自分に言い聞かせた。
やったんは、たにんの ひみつを かってに はなしては ならないと じぶんに いいきかせた。
Yattan told himself that he must not reveal other people's secrets without permission.
A moral rule Yattan is holding himself to, not just a passing wish.
人を差別してはならない。
ひとを さべつしては ならない。
One must not discriminate against people.
この装置は水に濡らしてはならない。
この そうちは みずに ぬらしては ならない。
This device must not be gotten wet.
Instruction-manual register — a broad rule, not a personal request.
Form: Verb-て + はならない
はならない attaches directly after the て-form of a verb, replacing the plain てはいけない you'd use in casual speech.
| Attaches to | Pattern | Example |
|---|---|---|
| Verb (て-form) | Vて + はならない | 忘れてはならない (must not forget) |
| Verb (て-form) | Vて + はならない | 諦めてはならない (must not give up) |
規則は破ってはならない。
きそくは やぶっては ならない。
Rules must not be broken.
Stronger and more formal than 〜てはいけない
〜てはいけない is the everyday version — a teacher telling a student, a parent telling a child. 〜てはならない is its formal cousin: written notices, laws, ethics statements, and speeches. It's rarely used to scold someone directly in conversation; instead it frames the prohibition as coming from a standard everyone is expected to follow, which also makes it sound more serious and less negotiable.
The short version
- 〜てはならない = "must not / should not" — a strong, formal prohibition.
- Attaches to: the て-form of a verb.
- Nuance/register: formal and impersonal; common in rules, laws, and moral statements.
- Don't confuse with: 〜てはいけない, the everyday version used in direct, personal prohibitions.
Practice it
Choose 〜てはならない when the sentence expresses a formal rule-based prohibition.
＿＿＿に入れるのに最もよいものを選びなさい。
図書館では大声で話し＿＿＿。
Where 〜てはならない fits
Shaky on this? Get these solid first
- Conditional 〜たら · N4 — 〜たら is Japanese's most flexible conditional: just add ら to the plain past. Learn the formation, the 'if/when' meaning, the discovery use, and how it beats ば/と for requests.
- 〜てください · N5 — 〜てください is the standard way to politely ask someone to do something ('please do…'). Learn the formation, the negative 〜ないでください, softer variations, and see clear examples.
Don't confuse it with
- 〜ねばならない · N2 — 〜ねばならない is the formal, literary way to say 'must / have to,' built from the negative conditional 〜ねば ('if not') + ならない ('won't do'). Common in writing, speeches, and rules.
- 〜てばかりは · N2 — 〜てばかりは pairs 'only/nothing but doing X' with a contrastive は to set up a negative like いられない or いけない — 'I can't just keep only doing X (something else needs attention).' It flags an action as excessive or one-sided.
- 〜てほしくない · N2 — 〜てほしくない is the negative of 〜てほしい — it says you don't want someone else to do something. 嘘をついてほしくない = 'I don't want you to lie.' Compare with the near-twin 〜ないでほしい.
- 〜ていかない · N2 — 〜ていかない is the negative of 〜ていく — it says a gradual change or ongoing process will not continue moving forward from now on. It negates the 'progressing away from the present' meaning of ていく.
More N2 grammar to explore
Keep going with related patterns at the same level:
- 〜てやがる — 〜てやがる attaches to the て-form to mark contempt, anger, or disdain toward someone's action — 'that jerk is doing X.' Rough, masculine, spoken register; never used in polite or formal speech.
- 〜てやまない — 〜てやまない attaches to the て-form of feeling verbs like 願う or 愛する to mean 'never cease to (feel this) / (feel this) from the bottom of my heart.' It marks an emotion that continues without a break.
- 〜と同時に — 〜と同時に attaches to a plain-form verb or noun to mean 'at the same time as / as soon as' — ベルが鳴ると同時に生徒が出た. It links two events happening simultaneously, or one triggering the other instantly.
- 〜ところだった — 〜ところだった means something almost happened but was narrowly avoided — 'I was just about to / I almost did.' It attaches to the dictionary form of a verb and often follows a close call like あぶない or もう少しで.
- つい — つい is an adverb meaning 'unintentionally / before I knew it' — it describes an action that slipped out despite the speaker's intentions, or a habitual slip. Common with speaking, eating, and other hard-to-control impulses.
- 〜は別として — 〜は別として means 'setting X aside' or 'apart from X' — it brackets off one topic as a separate matter so the speaker can address something more pressing, without denying the bracketed topic's importance.