A method for producing a catalyst for a fuel cell is provided which is capable of improving output characteristics of the fuel cell. Metal fine particles making up the catalyst for the fuel cell to be used as a fuel electrode and air electrode are formed by reducing platinum salt with molybdenum carbonyl. The catalyst for the fuel cell is formed by supporting platinum-molybdenum fine particles on carbon particles. By employing this reducing method, platinum-molybdenum fine particles being small in size and high in dispersibility can be obtained, making the catalyst for the fuel cell highly active. By constructing the fuel and air electrodes using the catalyst for the fuel cell, high outputs from the fuel cell are made possible.