In Taiwan and Japan, “basic act” is a special model of act that provide platforms, principles, or policies in specific administrative spheres without limiting the legal status of citizens or jurisdiction of an administrative agency. The legislative purpose of “basic act” is to regulate policymaking process and effectively control administrative power in a modern administrative state. In light of legislative purpose, this article explores the meaning and function of“basic act” from the perspective of how legislative power regulates the administrative policy in a specific administrative sphere. Since the concept of “ basic act” originated from Japan and Japanese law has deeply influenced Taiwanese law, this article will use Japanese “basic act” as a point of comparison, pointing out the potential problems and solutions, which will then offer constructive advice for Taiwanese legislation.