A membrane electrode assembly for a solid polymer electrolyte fuel cell includes an anode electrode, a cathode electrode, and a polymer electrolyte membrane sandwiched by the electrodes, the catalyst layer of the cathode electrode containing a catalyst supporting particle in which a precious metal is supported on heat-treated carbon black or activated carbon, an ion conductive material, and a crystalline carbon fiber. Heat treatment is preferably applied at 2,500 to 3,000.degree. C. (degrees Celsius).The membrane electrode assembly provides superior power generation performance.