Disclosed herein is a process of preparing a solid polymer electrolyte type fuel cell formed by combining a cathode current collector, a cathode containing cathode particles, an ion exchange membrane, an anode containing anode particles and an anode current collector characterized by comprising reducing a catalyst metal salt in an organic solution with the solid polymer electrolyte, depositing the reduced catalyst metal in the solid polymer electrolyte to form the cathode and/or the anode, interposing the cathode and/or the anode between the respective current collectors and the ion exchange membrane and pressing for assembling the fuel cell.Also disclosed is the same process as above except that the support is present in the solid polymer electrolyte.In the fuel cells prepared in accordance with the present invention, the catalyst metal always exists in the solid polymer electrolyte, and even if a cavity is formed in the solid polymer electrolyte, the catalyst metal is not exposed to the cavity. Accordingly, almost all the catalyst metals can be utilized to generate energy at the high efficiency.