Applying the concept of democratic accountability, this article argues that the operation of government system should conform to the principles of transparency, liability, controllability, responsibility, and responsiveness. As the French Fifth Republic is a typical regime of "double executive" (also known as "semi-presidentialism"), and the three periods of "cohabitation" also show its advantage in adapting to the political environmental change, our primary goal is to analyze the spirit and contents of French double executive regime. Secondly, this article identifies the institutional gaps between French and Taiwan. Although the gaps emerge from every dimension in Presidential power, the relations between President and Premier, and between the Executive Yuan and Legislative Yuan, further institutional replenishment is helpful to apply the double executive regime in Taiwan. Finally, this paper suggests that it is necessary to assess the double executive regime, so its function could be performed much better.