A membrane electrode assembly includes a cathode, an anode and a proton-conductive membrane, wherein the cathode includes a first metal-containing catalyst and a proton-conductive ionomer, the anode includes a proton-conductive ionomer, a second metal-containing catalyst that catalyzes the reaction of hydrogen to protons, and a third metal-containing catalyst that catalyzes the reaction of CO to CO2, a total mass ratio of platinum of the second catalyst and platinum of the third catalyst to a total mass ratio of metals of the second catalyst and the third catalyst, with the exception of platinum, is greater than 3:1, and the total mass per unit area of platinum of the second catalyst and platinum of the third catalyst is less than 0.4 mg/cm2.