Membrane-electrode assembly and fuel cell having the same

3A membrane-electrode assembly is characterized by including an electrolytic membrane having proton conductivity and a first electrode jointed on the electrolytic membrane. The first electrode has a catalyst and a first ionomer covering the catalyst and acting as a proton exchange group. A ratio of water-generation amount (mol/min) at rated output point of the membrane-electrode assembly/volume (cm) of the first ionomer in the first electrode is 1350 or larger.