In order to prevent an electrolyte membrane from being broken, and make an assembling steps of a cell easy, in a fuel cell provided with a membrane electrode complex in which catalyst layers are respectively arranged on both surfaces of a electrolyte membrane, first and second gas diffusion layers which are arranged on both surfaces of the electrode complex, separators for respectively supplying reaction gas to the first and second gas diffusion layers, and a gasket for sealing the reaction gas, the gasket is formed on a surface of the gas diffusion layer so as to oppose to the separator, at least the gasket forming portion of the gas diffusion layer has a lower void content than the portion in contact with the catalyst layer, and the gasket arranged in the first and second gas diffusion layers is integrally formed at least via a through hole passing through the first and second gas diffusion layers.