# こと: must do; rule to do > Learn how to use こと, a JLPT N3 Japanese grammar point meaning must do; rule to do, with structure, nuance, examples, mistakes, and comparisons. JLPT level: N3 · Updated: 2026-05-17 · Canonical: https://hane-app.com/blog/n3-koto/ **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 The best translation depends on the sentence. Try to notice the writer's or speaker's purpose first, then choose the English phrase that fits that context. ## How to form こと
Verb (dictionary form / ない-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 The form before the grammar point matters. In JLPT questions, the wrong answer choices often use a similar meaning but attach it to the wrong type of word. ## 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
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.
rule
レポートは金曜日きんようびまでに出だすこと。
Submit the report by Friday.
rule
教室きょうしつでは静しずかにすること。
Be quiet in the classroom.
instruction
大切たいせつな書類しょるいを忘わすれないこと。
Do not forget important documents.
rule
ここには車くるまを止とめないこと。
Do not park cars here.
notice
After reading each sentence, ask what job **こと** is doing: stating a rule, instruction, or requirement, often in notices. That makes the nuance easier to remember than a one-word translation. ## 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](/blog/n4-nakereba-naranai/)**, 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](/blog/n4-nakereba-naranai/)** can appear in related situations, but they are different.
こと
must do; rule to do
Fits the specific N3 pattern and nuance explained above.
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.
vs
なければならない
must do; have to
States obligation in a sentence.
なければならない states obligation in a sentence; こと gives a rule-like instruction.
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](/blog/n4-nakereba-naranai/)** and check whether the nuance still matches. If both translations seem possible, check the tone. Is the sentence a notice, a rule, a casual request, or an explanation? The tone often tells you which grammar point is natural. ## Common mistakes with こと
❌
友達に「早く来ること」
✅
友達には「早く来て」
Using こと as a casual request to friends sounds unnatural.
❌
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はいけません。
✅
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。
In rules, こと usually appears sentence-final in notices.
❌
日本語を勉強べんきょうすることは楽しいです。（as a rule）
✅
日本語を勉強べんきょうすることは楽しいです。（as a nominalizer）
Do not confuse this rule-use こと with the nominalizer こと.
## Is こと on the JLPT?
N3
Recognize it in reading
Understand its nuance in context
Use it in simple original sentences
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 For test preparation, study the grammar point in full sentences. JLPT questions often test whether you understand the surrounding context, not just the dictionary meaning. ## Practice questions for こと
1 Write a rule: submit by Monday. writing
2 Write a rule: do not enter. writing
3 Write a classroom instruction. writing
Keep your first sentences simple. Once the structure feels natural, add more context so the nuance becomes clear. ## 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.
1
First, make sure you can form こと without looking at the pattern chart.
2
Next, compare it with なければならない, ということだ. These patterns are close enough that choosing between them helps you understand the nuance.
3
Finally, write sentences about news, explanations, names, and hearsay; then check whether replacing こと with というのは changes the meaning.
## Related grammar to review next - [なければならない](/blog/n4-nakereba-naranai/) — because it is the closest comparison used in this article. - [ということだ](/blog/n3-to-iu-koto-da/) — because it is another pattern for quoting, defining, or reporting information. - [というのは](/blog/n3-to-iu-nowa/) — because it is another pattern for quoting, defining, or reporting information. - [と言うと（というと）](/blog/n3-to-iu-to/) — because it is another pattern for quoting, defining, or reporting information. ## 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](/blog/) - [JLPT N3 grammar lessons](/blog/n3/)