The classic definition of the administrative action implies an expression of will of the Administration intended to take legal effects; in this way, unilateral and discretional criteria have prevailed in their nature; however, this research provides new statements on such nature from the nonexistence of the administrative discretion, in order to set the proper criterion in the juridical definition and nature of the administrative action. This article contains reflections and arguments from the Colombian doctrine, jurisprudence, and legislation, but holding a criterion of compared law which allows making a proper analysis of the topic.