According to the new institutionalism, the state is the organization that has the comparative advantage on force. The basic role of state is to provide law and order, to protect the nature rights in return for tax revenue. Owing to its advantages such as compulsory, monopoly and scale economy, the state plays a unique and important role on political institutional change. According to the basic viewpoint of the new institutionalism, the paper explores the relation between the political institutional change and state. It includes three parts.The first part analyses the theory of state on political institutional change. The state's economic man nature is the motivation it wants to change the political institution. Marxism holds that the state's class nature is one of the reasons the political institution changes. At the same time, the compulsory, scale economy and monopoly make the state conquer externalities, reduce the pick up phenomenon, cost saving and increase earning.The second part explores the role of state on political institutional change. Change constitutional order will influence the demand, confine, direction, fashion, knowledge foundation and supply ability of political institutional change, also the cost and difficulty. Reforming ideology will conquer the pick up phenomenon, reduce the exchange cost, and harmonize formal and informal institutional change. Increasing social science will enlarge the confine of political institution innovation. Promoting compellent political institutional change will convert the civilian and social demand on political institution to supply, provide the support and restriction for the epigamic political institutional change, and resolve the urgent demand of change. The institutional innovation which is leaded by state is the cheapest innovative form, and the state can reduce the change cost also by compulsory, scale economy and economical method.The third part expounds the state's localization on political institutional change. The state is astricted by The North Antinomy, the ruler's limited sense, the ruler's many-faceted hobby and the diversion of the interest group. The compellent political institutional change will not be the proximate to the realism or reflect the dispersive demand. The state will be astricted by the ideology and constitution. Besides, the bureaucracy's selfish trend will lead the political institution to be executed by lower efficiency. |