To provide a power generating system capable of carrying out temperature control of suction air without causing a compositional change of the suction air and extra energy consumption.

Into an air suction chamber into which air is sucked, air is introduced which flows out of an outflow port of an outer shell encircling the outer wall of a combustion chamber and a gas turbine chamber. A space between the outer wall of the combustion chamber and the gas turbine chamber and the outer shell has a temperature higher than that of outside air with radiation heat from the combustion chamber and the gas turbine chamber. Power generating efficiency is therefore improved by controlling the amount of air flowing into the air suction chamber when the temperature of the suction air is low. No extra energy consumption is caused because it is originally necessary to ventilate air between the outer wall of the gas turbine chamber and the outer shell.