Abstract: Under the background of frequent mass environmental incidents in contemporary China,the investigation of Japanese environmental protests in 20th century not only provides a reference for the current Chinese environmental governance,but also contributes to the theoretical development of social movement studies.Based on Japan's Minamata Disease protests occurred from 1950s to 1970s,this article explores how the political opportunity structures changes affect the environmental protests.By collecting the literature and implementing field research on Minamata disease protests,we divide the process of Minamata disease protests into three phases,"pre-protests" phase (1956-1959),"political opportunity structure expansion" phase (1960-1968),and "development of protests" phase (1969-1973).Why did the protests of Minamata disease evolve from scattered local riots to disappearance,then rose gradually and affected the whole country in the late 1960s? One of the most important mechanisms was the expansion of political opportunity structures in 1960s.The Expansion of political opportunity structures prompted the development of Minamata disease protests through four aspects,which are the expansion of protest organizations scale,the rise of protests issues,the acceleration of internal division of bureaucracy system,and the reinforcement of importance of environmental dialectic.

Key words: Minamata disease, environmental protest, environmental governance, political opportunity structur, environmental movement