SOLID OXIDE FUEL CELL

To provide a solid oxide fuel cell of the present capable of improving overall energy efficiency. The present invention is a solid oxide fuel cell (1) having: a fuel cell module (2); a fuel supply device (38); a combustion chamber (18) for burning residual fuel and heating; a heat storing material (7), a power demand detecting sensor (126); a temperature detection device (142), and a control device (110) for controlling so that the fuel utilization rate is high when generated power is large, and also for changing output power at a delay to the fuel supply amount; whereby the control device is furnished with a stored heat amount estimating circuit (110b), and when it is estimated that a usable heat amount has accumulated in the heat storing material, the fuel supply amount is reduced so that the fuel utilization rate increases vs. the same generated power.