ことkoto“must do; rule to do”

こと means must do; rule to do. It is a JLPT N3 grammar pattern used to state a rule, instruction, or requirement, often in notices.

This grammar point often appears in formal written instruction Japanese. If you want to state a rule, instruction, or requirement, often in notices, こと is a useful pattern to learn.

What does こと mean?

Use こと when you want to state a rule, instruction, or requirement, often in notices.

Natural translations include:

• must do; rule to do
• must do
• must do / rule to do

How to form こと

Examples of the pattern:

• 静かにすること
• 忘れないこと
• 入らないこと

When is こと used?

Use こと in situations like:

• school or workplace rules
• written instructions
• teacher or parent reminders

Tone and register:

• formal written instruction
• Common in JLPT reading, grammar questions, and natural Japanese sentences

こと example sentences

After reading each sentence, ask what job こと is doing: stating a rule, instruction, or requirement, often in notices.

Nuance of こと

The key nuance is sounds like an official rule rather than a personal request.

This matters because こと does more than translate one English phrase. It tells the reader how the speaker is framing the situation, whether as emphasis, contrast, obligation, approximation, or evidence.

For example:

• In context, it sounds natural when the surrounding sentence supports the nuance.
• Compared with なければならない, it has a different focus and level of formality.

こと vs なければならない

Both こと and なければならない can appear in related situations, but they are different.

Quick contrast examples:

• Target: 試験中(しけんちゅう)は携帯電話(けいたいでんわ)を使(つか)わないこと。 — Do not use mobile phones during the exam.
• Compare: Try replacing it with なければならない and check whether the nuance still matches.

Is the sentence a notice, a rule, a casual request, or an explanation?

Common mistakes with こと

Is こと on the JLPT?

Yes. こと is commonly taught as JLPT N3 grammar.

That means learners should be able to:

• recognize it in reading
• understand its nuance in context
• use it in simple original sentences

Practice questions for こと

Learning path for こと

To learn こと efficiently, review と言う and quotation basics, then practice whether the sentence reports, defines, rephrases, or introduces a topic.

Related grammar to review next

• なければならない — must do; have to.
• ということだ — I heard; it means that.
• というのは — what … means is; because.
• と言うと（というと） — speaking of; when you say.

Learn こと with Hane

If you want to review こと together with the related patterns above, Hane helps you connect grammar, kanji, and vocabulary in short, focused sessions.

Browse more lessons here:

• All grammar lessons
• JLPT N3 grammar lessons