In Japanese, “yes” (はい, ええ, うん, etc.) or “no” (いいえ, いや, ううん, etc.) as a response to a question signify if the question as the statement is correct or not, NOT if your response is positive or negative. This gets very confusing for English speakers, when the original question is a negative sentence. See the below examples:

• タバコは吸いますか？はい、吸います -> Do you smoke? Yes, I do
• タバコは吸いますか？いいえ、吸いません -> Do you smoke? No, I don’t
• タバコは吸わないんですね？はい、吸いません -> You don’t smoke, do you? Yes (that is correct), I don’t smoke
• タバコは吸わないんですね？いいえ、吸います -> You don’t smoke, do you? No (that is not correct), I do smoke
• それ知らなかったの？うん、知らなかった -> You didn’t know that? Yes (that is correct), I didn’t know

As in the English translations, Japanese はい and いいえ mean “yes, your statement is indeed correct” or “no, your statement is incorrect”.

This can get very confusing between English speakers and Japanese speakers. In order to avoid miscommunications, it is better to reply in a complete sentence instead of just say はい or いいえ. If you reply using the English way while speaking Japanese, it will confuse your listener, but at least it will create a chance to clarify things from both sides, instead of the misunderstanding goes unnoticed.