Learn 理由 vs 原因 in Chinese (China, Simplified). Build fluency with personalized exercises, chats, and video recommendations.
理由 and 原因 both mean "reason," but they are used differently:
理由: means a "reason" in the sense of a justification or rationale—often used to support an opinion or decision. It’s what you cite as your reason for doing something (我有充分的理由这么做 = I have a good reason for doing this).
原因: refers to the "cause" or underlying factor that leads to a result or event—the fundamental reason something happened (事故的原因还在调查中 = The cause of the accident is still under investigation).
Common pattern: 理由 often comes after 没有 (没有理由 = no reason/motive) or 很好的 (很好的理由 = a good reason), while 原因 often appears in questions like 原因是什么？ (= what is the cause/reason?) or in compound nouns like 原因分析 (= root cause analysis).