To generate electric power directly by conducting the electrochemical reaction between the hydrogen of the fuel hydrogen and the oxygen of an oxidizing agent utilizing solid high polymer electrolyte.

An electric heater 11 is provided in a reforming instrument 5 which heats and reforms methanol water M into hydrogen-rich fuel hydrogen, and electricity generated by a fuel cell 9 or a power generating device besides the fuel cell 9 is fed to the electric heater 11 so as to reform. Thereby, reforming by the burning of the remaining fuel hydrogen RH fluctuating on the size of an external load is equalized by the reforming through the heating of the electric heater 11 so that no uneasiness of the burning is allowed so as to facilitate its operation.