N3 Advice, Obligation, and Prohibition

~ことだ: meaning, usage and examples

~ことだ means: you should... (used for giving advice).

Updated 9 November 2026 · By the My Senpai team · Spotted a mistake? Tell us

Examples

1. かぜをひいたなら、ゆっくり休やすむことだ。

   If you have a cold, you should relax and rest.

2. 強つよくなりたければ、毎日練習まいにちれんしゅうすることだ。

   If you want to get stronger, you should practice every day.

3. 日本語にほんごが上手じょうずになりたければ、毎日まいにち話はなすことだ。

   If you want to get better at Japanese, the key is to speak it every day.

4. 疲つかれているときは、無理むりをしないことです。

   When you're tired, the best thing is not to push yourself.

When to use it

ことだ gives advice: "you should," "the best thing is to." The speaker says what someone needs to do to reach a goal or fix a problem. It often follows a condition with たら, なら, or ば: 上手じょうずになりたいなら、毎日まいにち話はなすことだ ("If you want to get good, speak every day").

Nuance

Sounds like advice from someone older or more experienced, so it can feel a little superior. It is not used toward people above you. The advice is usually general and practical, and the pattern appears often in advice columns.

Compare

ほうがいい is softer, everyday advice: 休やすんだほうがいい. べきだ is a moral duty: 約束やくそくは守まもるべきだ. こと without だ is a rule or an order: 休やすむこと. ことだ offers the one key piece of advice.

Tip: Think "The best thing is to..." The negative ないことだ means "the best thing is not to," as in 無理むりをしないことだ.