A membrane electrode assembly of a fuel cell includes a solid polymer electrolyte membrane, a cathode, and an anode. The surface size of a cathode side electrode catalyst layer of the cathode is smaller than the surface size of an anode side electrode catalyst layer of the anode. An inner end of a gas impermeable film provided around the anode side electrode catalyst layer and an outer end of a cathode side electrode catalyst layer are overlapped with each other on both sides of the solid polymer electrolyte membrane.