A polymer electrolyte fuel cell comprising: a solid polymer electrolyte membrane containing an aromatic polymer electrolyte; an electrode comprising a catalyst layer and a gas diffusion layer as an anode and a cathode to be joined on both surfaces of this solid polymer electrolyte membrane; a gas sealing material to be disposed in a periphery of the gas diffusion layer; and a separator having a reaction gas flow field; wherein said gas diffusion layer surrounds the whole outer edge of the gas flow field of said separator and has a larger area than an area occupied by the outer edge of the gas flow field of said separator is provided.