A solid oxide fuel cell C including a solid oxide fuel cell having a planar solid oxide substrate, a cathode electrode layer formed on one surface of the substrate, and an anode electrode layer formed on a surface opposite the one surface, is disposed so that the anode electrode layer opposes a catalytically-oxidizing member 13 of a heating appliance. Fuel supplied from a fuel storage container 10 is subjected to flameless combustion in the catalytically-oxidizing member by catalytic oxidation. The heat is conducted to the fuel cell C from the catalytically-oxidizing member, thereby maintaining the fuel cell at its operating temperature. Simultaneously, produced oxidation fuel components of the fuel are supplied to the anode electrode layer; and air is supplied to the cathode electrode layer. Hence, the fuel cell generates electric power.