ないほうがいいIt is better not to
ないほうがいい advises someone that avoiding an action is the better choice in the situation. It is common for warnings about health, safety, etiquette, and other unwise choices.
How it works
The speaker considers two choices—doing something or avoiding it—and recommends avoidance. A reason or clear situation often makes the advice sound more natural and considerate.
A safety warning
今夜は車で行かないほうがいいよ。雪が降りそうだから。
You'd better not go by car tonight. It looks like it's going to snow.
AnalyzeAsking what would be better
雨が強くなってきました。今日は出かけないほうがいいですか。
The rain is getting heavier. Would it be better not to go out today?
AnalyzeAdvice versus prohibition
ないほうがいい recommends avoiding an action. By contrast, てはいけない says that the action is not allowed. The difference is the force of the message, not simply politeness.
More examples
体調が悪いなら、今日は無理をしないほうがいいですよ。
If you're not feeling well, you'd better not push yourself today.
Analyze夜遅いから、一人で歩かないほうがいいよ。
It's late, so you'd better not walk alone.
Analyze大事なメールは、急いでいるときに送らないほうがいいです。
It's better not to send an important email when you're in a hurry.
Analyzeその話は、本人がいないところでしないほうがいいと思います。
I think it's better not to discuss that when the person concerned isn't there.
Analyzeこの道は雨の日に滑りやすいので、通らないほうがいいです。
This road gets slippery on rainy days, so it's better not to use it.
Analyze会議の前に、このことをみんなに言わないほうがいいですか。
Would it be better not to tell everyone about this before the meeting?
Analyze
A social choice
初対面なら、いきなり年齢を聞かないほうがいいと思います。
With someone you have just met, I think it's better not to ask their age right away.
AnalyzeAdding “I think” makes personal advice sound less forceful.