In a solid oxide fuel cell, the nonuniformity of temperature distribution in the axial direction of a solid electrolyte, the decrease in cell performance caused by a decreased effective cell reaction area, and the damage to cell due to thermal stress generated by a temperature difference are restrained. A reforming catalyst is provided in a high-temperature portion on the anode side to cool the high-temperature portion by means of heat absorption of reforming reaction, or a combustion catalyst is provided in a low-temperature portion on the anode side to heat the low-temperature portion by means of heat generation of combustion reaction, or both of the catalysts are provided, by which the occurrence of variations in temperature in a cell reaction region of anode is prevented. In addition, an air flow from an air introduction tube of cathode is branchingly sprayed so that a cooling effect is produced in the high-temperature portion, by which an effect of restraining the variations in temperature can further be increased.