A close attachment region is provided on the outer side relative to an outer edge portion of a gas diffusion layer and on the inner side relative to the inner edge portion of a gasket as seen from the thickness direction of a polymer electrolyte membrane, such that separators and a frame member are closely attached to each other. Thus, it becomes possible to suppress an increase in the manufacturing cost and a reduction in the power generation performance, which is attributed to the impurity eluted from the gasket and flowing toward the gas diffusion layer.