should not do~; must not do~ (べきではない) – Japanese Grammar べきではない (beki dewa nai)

Q: What JLPT level is べきではない?

JLPT N3 — Intermediate · Expressing nuance & contrast

Q: How do you use べきではない in a sentence?

Attach べきではない to the appropriate verb or noun form. Should not do~; must not do~

Q: Is べきではない formal or casual Japanese?

べきではない can be used in both casual conversation and polite speech depending on context.

べきではない

N3 GRAMMAR ⏱ 0s study 📖 0 today

beki dewa nai

should not do~; must not do~

ようとする you to suru ずに zuni ば～のに ba~noni にとって ni totte なんか / なんて nanka / nante ような気がする you na ki ga suru ずにはいられない zuni wa irarenai のでしょうか no deshou ka てはいけないから te wa ikenai kara 通す toosu 上で ue de うちに uchi ni というのは to iu nowa べきだ beki da 割に wari ni たとえ～ても tatoe~temo むしろ mushiro つもりで tsumori de 合う au 上に ue ni ようとする you to suru ずに zuni ば～のに ba~noni にとって ni totte なんか / なんて nanka / nante ような気がする you na ki ga suru ずにはいられない zuni wa irarenai のでしょうか no deshou ka てはいけないから te wa ikenai kara 通す toosu 上で ue de うちに uchi ni というのは to iu nowa べきだ beki da 割に wari ni たとえ～ても tatoe~temo むしろ mushiro つもりで tsumori de 合う au 上に ue ni

🃏 Flashcard

べきではない

beki dewa nai

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should not do~; must not do~

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📊 Pattern Stats

JLPT Level N3

Intermediate · Expressing nuance & contrast

Reading beki dewa nai

Post ID 50824

Patterns today 0

0 / 10 daily goal

📝 Usage Notes

should not do~; must not do~

📖 How to use it

Says that doing something is wrong or inadvisable; a strong 'should not'.

Attaches to Attach to the dictionary form of a verb. For nouns and na-adjectives, use 'であるべきではない' (or 'なべきではない' for na-adj, but 'である' is more common). For i-adjectives, use 'べきではない' after the adjective's dictionary form.

This pattern expresses a strong moral or practical judgment that something should not be done. It is more forceful than 'ないほうがいい' (better not to) and carries a sense of obligation or ethics. For example, '遅刻するべきではない' means 'You should not be late' — it implies that being late is wrong, not just inconvenient.

It is formed from the verb 'べき' (which comes from the classical 'べし') plus 'ではない'. When using nouns, you need 'である' before it: '学生であるべきではない' (should not be a student) — but this is rare. More common is with verbs. In speech, it sounds strong and a bit preachy, so it is often used in advice, warnings, or societal commentary. For personal advice, 'ないほうがいい' is softer.

Note: The negative form 'べきではない' is often shortened to 'べきじゃない' in casual speech, but be careful — 'べきじゃない' can also be used with a softer tone. Stick with 'べきではない' for formal or written contexts.

約束を破るべきではない。

Yakusoku o yaburu beki dewa nai.

You should not break a promise.

他人の悪口を言うべきではないと思います。

Tanin no waruguchi o iu beki dewa nai to omoimasu.

I think you should not speak ill of others.

お金を無駄に使うべきではないよ。

Okane o muda ni tsukau beki dewa nai yo.

You should not waste money.

Not ～てはいけない～てはいけない is a rule or prohibition (must not), while べきではない is a moral or logical judgment (should not). For example, 'ここでタバコを吸ってはいけない' is a rule, but 'タバコを吸うべきではない' is advice based on health or ethics.

Register Formal and written; in speech it sounds strong and preachy, so it is often used in essays, speeches, or serious advice.

🎯 Quick Quiz

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べきではない

📚 How to Master This Pattern

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Press Hear it and repeat べきではない three times. Feel the rhythm — grammar patterns have a natural flow.

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Compose two original sentences using べきではない. One about yourself, one about something you see right now.

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🔗 More JLPT N3 Patterns

not really, not particularly

❓ Frequently Asked Questions

What does the grammar pattern べきではない mean? ▼

Should not do~; must not do~

What JLPT level is べきではない? ▼

Nihoner currently groups this pattern under JLPT N3 — Intermediate · Expressing nuance & contrast. Use the level label as study guidance rather than a prediction of what will appear on an exam.

How do you use べきではない in a sentence? ▼

Attach べきではない (beki dewa nai) to the appropriate verb or noun form as described in the usage notes. Then try writing two original sentences — one about yourself and one about something around you.

Is べきではない formal or casual Japanese? ▼

べきではない is used in both casual and polite contexts. It appears frequently in everyday conversation, textbooks, and simple written materials.

How can I remember べきではない long-term? ▼

Use the flashcard on this page for active recall — see the pattern, reconstruct the usage from memory, then flip. Follow with the 4-choice quiz to distinguish it from similar patterns. Review later the same day and again over the following days. Writing original sentences can help you practise using the pattern in context.