JLPT N1ComparisonUpdated 2026-09-25

べからず vs まじき vs てはならない bekarazu · majiki · te wa naranai

べからず is an old-style prohibition, まじき means unbecoming, and てはならない means must not. 立ち入るべからず forbids entry in an archaic style. 教師にあるまじき行為 judges conduct against a role. てはならない is a direct formal prohibition used in rules; everyday speech often uses てはいけない instead.

also written bekarazu / majiki / tewa naranai / 立入禁止

べからず — the sign on the fence · まじき — unbecoming of someone in that position · てはならない — the ordinary written prohibition

Sentences

6 sentences, word by word

べからず — the sign on the fence

plain

。

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立入る

たちいる［0］

enter; set foot in

godan verb · dictionary form, and the 送り仮名 is often dropped on signs

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べからず

do not

classical negative of べし · survives mainly on signage

べからずN1do not · classical

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No entry.

べからざる — the attributive form

plain

。

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それ

that

pronoun · the act under discussion

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は

as for — the topic

particle · written は, read わ

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許す

ゆるす［2］

forgive; permit

godan verb · dictionary form before べからざる

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べからざる

that must not be

attributive べからず · the form that modifies a noun

べからざるN1that must not be · attributive

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行為

こうい［1］

act; conduct

noun · formal; 行動 is behaviour more broadly

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だった

was

plain past copula · closing the verdict

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It was an unforgivable act.

まじき — measured against a role

plain

。

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それ

that

pronoun · the act being judged

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は

as for — the topic

particle · written は, read わ

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教師

きょうし［1］

teacher

noun · the role the act is measured against — まじき requires one

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に

for; of

particle · part of 〜にあるまじき — it names the role, not a destination

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あるまじき

unbecoming of

classical · 〜にあるまじき, the only shape まじき really appears in

にあるまじきN1unbecoming of

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行為

こうい［1］

conduct

noun · what まじき almost always modifies

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だ

plain copula · the verdict stated flatly

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That is conduct unbecoming of a teacher.

てはならない — the written rule

plain

。

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この

this

demonstrative · the experience just referred to

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経験

けいけん［0］

experience

noun · 経験する to experience something

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を

marks the direct object

particle · pronounced お

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忘れて

わすれて

forget

て-form of 忘れる · what はならない attaches to

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は

(part of てはならない)

particle · the は of the prohibition frame, not a topic marker

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ならない

must not

negative of なる · the written prohibition, neutral in tone

てはならないN1must not · written

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You must never forget this experience.

てはいけません — said to a person

polite

。

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芝生

しばふ［0］

grass; lawn

noun · a planted lawn, not 草 growing wild

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に

to; at; into

particle · a point something reaches — a place, a time, a person, or a state

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入って

はいって

go onto

て-form of 入る · 芝生に入る, to step onto the lawn

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は

(part of てはいけない)

particle · same frame は as てはならない above

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いけません

must not

polite negative potential of いく · what a person says to a person

てはいけないN4must not · spoken

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You mustn't walk on the grass.

べからず — the proverb

plain

。

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初心

しょしん［0］

one's original intention

noun · the beginner's resolve you had at the start

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忘る

わする［2］

forget

classical form of 忘れる · preserved inside the proverb

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べからず

must not

classical negative · this proverb is where most people meet it

べからずN1must not · classical

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Never forget where you started.

Structure

How each one is built

入る / 忘る＋べからず

立入るべからず. する becomes すべからず. The attributive form べからざる modifies a noun: 許すべからざる行為.

教師 / 学生に＋あるまじき＋行為 / 発言

教師にあるまじき行為. The role is compulsory — the whole point is measuring the act against what that position demands.

忘れ / 入っ＋てはならない

忘れてはならない. Productive with any verb, and the register of a written rule rather than a sign.

Verb ［て］＋はいけない

入ってはいけません. What a person says to another person. The three above are for signs, judgements and documents.

Meaning

A sign, a judgement, and a rule

べからず is classical, and you will mostly read it. 立入るべからず on a fence, 初心忘るべからず as a proverb. It is the negative of the old べし, and producing it in ordinary prose sounds like costume drama.

まじき needs a role to measure against. 教師にあるまじき行為 — conduct unbecoming of a teacher. The condemnation is not that the act was bad in general, but that someone in that position did it.

てはならない is the workaday written prohibition. Contracts, safety notices, school rules. It carries no archaism and no judgement about character — it simply forbids.

てはならない is productive for direct prohibition. It attaches to verbs in formal rules. べからず is mostly seen in set or stylized writing, while まじき often occurs as 〜にあるまじき before a noun.

The spoken form is てはいけない. Said to a person, even てはならない is stiff — a sign says ならない, a teacher says いけません, and a friend says だめ.

Watch out

Where these three go wrong

まじき without a role

The pattern measures an act against a position, so it needs one: 教師にあるまじき, 学生にあるまじき. On its own it has nothing to compare against.

Using べからず in ordinary writing

It reads as archaic. An email or a report wants てはならない; べからず belongs on a sign or inside a proverb.

てはならない spoken to someone

It is the register of a document. To a person, てはいけません — or だめ between friends.

Also asked

Questions people ask about these three

Which one would I actually use?

てはならない if you are writing a rule, and てはいけません if you are speaking to someone. The other two are for recognition.

Why does まじき need a role in front?

Because the judgement is comparative — the act is unbecoming of someone in that position. Without the role there is no standard to fall short of.

What is べからざる?

The attributive form, used before a noun: 許すべからざる行為. べからず ends a sentence; べからざる modifies.

How does する behave with べからず?

It becomes すべからず, from the classical す. The same irregularity gives you すべき in the positive.

Is 初心忘るべからず everyday Japanese?

The proverb is, and the grammar inside it is not. People quote it whole, much as an English speaker quotes a line of Shakespeare without adopting the syntax.