NOVELTY - The solid polymer electric power generating apparatus (1) has an electric power generating cell (14) having bipolar plates (21,22) connected to an electrode via gas diffusion layers (19,20). Fuel and oxidant gas supply switching valves (10,12) change the connection of each fuel gas supply path (5) with the corresponding oxidant gas supply path (6), allowing the switching of the output polarity of a pair of electrodes to either a fuel electrode or an oxygen electrode.    USE - Solid polymer electric power generating apparatus.    ADVANTAGE - The supply of fuel gas is stopped with respect to this one electrode when one electrode is involves in carbon monoxide poisoning, thus supplying oxidant gas, minimizing damages with respect to the oxidation removal of carbon monoxide at the shortest time possible which in turn results in continuous production of electricity. Prevents mixing of fuel gas with oxidizing gas since fuel gas and an oxidant gas are not simultaneously supplied with respect to one electrode, thus preventing damage to the solid polymer electrolyte and the corresponding electrode. Ensures efficient removal of carbon monoxide contamination on one electrode since the carbon monoxide content of fuel gas is reduced before fuel gas is supplied to an electrode, thus reducing the amount of carbon monoxide which can be adsorbed by the electrode by which fuel gas is supplied.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following:    (1) a solid polymer fuel system; and    (2) an electric power generation method.    DESCRIPTION OF DRAWING(S) - The drawing shows the schematic circuit diagram of the solid polymer electric power generating apparatus. (Drawing includes non-English language text).    Solid polymer electric power generating apparatus (1)    Fuel gas supply path (5)    Oxidant gas supply path (6)    Fuel gas supply switching valve (10)    Oxidant gas supply switching valve (12)    Electric power generating cell (14)    Gas diffusion layers (19,20)    Bipolar plates (21,22)