For a proton exchange membrane fuel cell, membrane and electrode assemblies were fabricated by differ-ent hot pressing conditions and those performances were observed in a unit cell having 5cm² active electrode area. The cell performance increased with lower hot pressing temperature in the range of temperature having intimate contact between membrane and electrodes and with higher hot pressing pressure. Namely, the performance of proton exchange membrane fuel cell could be raised with higher water content in the membrane, Namely, the performance of proton exchange membrane fuel cell could be raised with higher water conent in the membrane, with lower contact resistance between membrane and electrodes and with lower ion resistance of the electrolyte using thinner membrane.