A fuel cell includes a plurality of electrolyte electrode assemblies and a pair of separators sandwiching the electrolyte electrode assemblies. A fuel gas supply channel formed by a channel member fixed to the separator is connected to a fuel gas inlet formed in an inner end of a trapezoidal section. Unburned hydrogen in an exhaust fuel gas consumed in the reaction at the anode, and discharged from the fuel gas channel to an oxygen -containing gas supply unit, is mixed with an oxygen-containing gas before consumption, burned, and then supplied to an oxygen-containing gas channel.