This study examined the constitutional engineering of the Philippine democracy in terms of power sharing and accountability, and the effectiveness and stability of the Philippine democracy as a result were assessed. Based on the analysis, the nature of the present Philippine democratic system since 1986 was brought to light. This study argues that the system of power sharing between the President and the congress in the Philippines tends to serve for negotiating political interests among the power elites rather than functioning in a constructive way. And the public accountability system is not functioning as it was designed to do. Due to the defects the Philippine democracy continuously suffers the lack of political effectiveness and stability. Despite of the problem, the reason not to break down the system would be the fact that the system served for the oligarchic power elites to circulate and recreate the political power exclusively. The direction of the Philippine constitutional engineering should be weakening the present traditional elite dominated political system, and strengthening the chances of political participation from the various classes. Some concerned people suggested the constitutional change to parliamentary system in order to strengthening party politics, and federal system to cope with the problems of regional conflicts, but such efforts failed repeatedly due to the conflict of political interests. Considering the present circumstance, it would be advisable to reform political party law and election system in the direction of strengthening political party system, and to expand the scope of local government system in the direction of devolving the centralized political power.