N3 · Structured courses

~Mono Dewa Nai: Should Not / One Must Not

Learn mono dewa nai for general prohibition or advice based on common sense. This lesson combines form, context, examples, common mistakes, and practice so you can use the pattern in real communication.

12 minNihongo Hub Editorial TeamPublished 2026-06-06Updated 2026-06-06

Learning objectives

  • Lesson goals: Learn mono dewa nai for general prohibition or advice based on common sense.
  • Form and connection: [Verb辞书形/なi-adjective] ものではない
  • Nuance in real use: ものではない appeals to "the way of the world" — it's not "I forbid you" but "nobody in this world should do that." This appeal to universal truth is common in Japanese moral education.

Form and connection

[Verb辞书形/なi-adjective] ものではない

Core Explanation

Learn mono dewa nai for general prohibition or advice based on common sense.

Cultural Note

ものではない appeals to "the way of the world" — it's not "I forbid you" but "nobody in this world should do that." This appeal to universal truth is common in Japanese moral education.

Practical examples

One should not speak ill of others.
Promises should not be broken.

Common pitfalls

Build the base form before adding the pattern

Complete the required conjugation first. Do not keep polite and plain endings at the same time.

Match politeness to the situation

The examples are reliable starting points; relationships and context can still change the most natural wording.

Practice and answers

1. Write the connection formula for this lesson.
Show answer[Verb辞书形/なi-adjective] ものではない
2. Explain the meaning of the first example.
Show answerOne should not speak ill of others.
3. Rewrite the final example using this lesson pattern.
Show answer約束やくそくは破やぶるものではない。 ([Verb辞书形/なi-adjective] ものではない)

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