Article II of the ROC constitution states,“The sovereignty of ROC belongs to nation", which underlines the presence of popular sovereignty. However, how concrete “popular will" delivers and influences the manipulation of state authority remains unclear. This article mainly describes the need of state authority to equip with democratic legitimacy under principle of popular sovereignty. It is not admitted literally the “lack of democratic legitimacy" within the scope of state authority. Although diverse interpretative module and delivery path existing in theory and comparative law, the main purpose of this article lies in proving and interpreting how each state authority covers and accepts the delivery module and path controlled by popular will under ROC constitution, so as to abandon the false democratic myth that “public referendum is the only path to reach democratic legitimacy". Hence, a sound democratic system lays not merely in holding reelection periodically, but in seeking proper method to cover popular will under state authority, so as to take responsibility to the popular. Moreover, to protect popular political freedom and establish social consensus are the main goal to pursue.