行政行为的公定力是指行政行为一经成立,即被推定为合法有效而予以尊重的法律效力。本文探讨了公定力的概念溯源、公定力的理论依据,在理论依据问题上我们赞同“适法推定说”。在公定力的界限问题上,本文认为“有限公定力说”符合现代法治理念,从实质正当性出发,以保护相对人的合法权益为目的。 Legitimacy of administrative behavior refers to the administrative act once established, that is presumed to be valid and valid and respected the legal effect. This article explores the concept of the official force traceability, the theoretical basis of the official force, on the theoretical basis of the issue we agree with the “presumption of presumption of fitness.” On the boundary of public power, this paper argues that “limited power” is in conformity with the concept of modern law and from the perspective of substantive legitimacy, with the purpose of protecting the legitimate rights and interests of relative people.