Combustor temperature control of a fuel cell power plant

A reformer (6) generates hydrogen rich gas from vaporized methanol and a fuel cell stack (8) generates electric power by a reaction of hydrogen rich gas. A combustor (10) generates heat due to combustion of fuel and supplies it to a vaporizer (5) for vaporizing liquid methanol. A controller (100) increases a fuel supply amount to the combustor (10) when the methanol supply amount to the vaporizer (5) is increased. The controller also calculates a prediction temperatures of the combustor (10) (S5) and suppresses the fuel supply amount when any one of the prediction temperature is lower than a predetermined temperature (S6, S8A).