NOVELTY - A membrane electrode assembly (5) comprises an electrolyte membrane (1) containing a polymer electrolyte resin and catalyst layers (2a, 2b) containing a polymer electrolyte resin, both having a proton dissociating polar group and a catalyst component on both surfaces of the electrolyte membrane. At least one of the catalyst layers contains a fullerene derivative having a proton dissociating polar group.    USE - For a fuel cell (claimed).    ADVANTAGE - The fullerene derivative enters into the cluster and thus the size of the cluster is fixed, this provides an electrode expressing stable proton conductivity. Unlike the polymer electrolyte resin, the fullerene derivative does not excessively cover the surface of the catalyst component and the conductive material carrying the catalyst component. Thus, it is easy to secure the electron conductivity by the conductive material. In addition, the presence of the fullerene derivative at the interface between the electrolyte membrane and the electrode improves the joint between the electrolyte membrane and the electrode. An improvement in the joint between the electrolyte membrane and the electrode improves the proton conductivity between the electrolyte membrane and the electrode and the durability of the membrane electrode assembly. In the catalyst layers in the membrane electrode assembly, a proton is supplied to the catalyst component and moved from the catalyst component to the electrolyte membrane efficiently even at low current range, thus maintaining high electrode reactivity. The membrane electrode assembly exhibits excellent power generation performance over a wide current range from the high current range to the low current range can be obtained by the combined use of the polymer electrolyte resin and the fullerene derivative as a solid electrolyte in the catalyst layer.    DETAILED DESCRIPTION - A membrane electrode assembly comprises an electrolyte membrane (1) containing a polymer electrolyte resin and catalyst layers (2a, 2b) containing a polymer electrolyte resin, both having a proton dissociating polar group and a catalyst component on both surfaces of the electrolyte membrane. At least one of the catalyst layers contains a fullerene derivative having a proton dissociating polar group. Assuming that the total quantity of the polymer electrolyte resin and the fullerene derivative is 100 wt.%, the content of the fullerene derivative is present in an amount 35-75 wt.%. An INDEPENDENT CLAIM is included for a fuel cell.    DESCRIPTION OF DRAWING(S) - The figure shows a cross-sectional view of the unit cell.    electrolyte membrane (1)    catalyst layer (2a, 2b)    cathode (4a)    anode (4b)    electrode assembly. (5)