Gas turbine apparatus

A gas turbine apparatus is provided which comprises a turbine, a combustor for burning a mixture of air and fuel and providing the turbine with a combustion gas to drive it, a generator connected to the turbine to receive rotational force therefrom to generate electric power, a temperature sensor for measuring a temperature of an exhaust gas from the turbine, a temperature setting unit and a power setting unit. The power setting unit sets a set output power of the generator such that a first set output power is set when starting-up the generator, the first set output power is decreased at a first rate when the measured exhaust gas temperature reaches a second set temperature higher than a first target temperature, a currently set output power is decreased at a second rate higher than the first rate when the measured exhaust gas temperature reaches a third set temperature higher than the second set temperature after decreasing the set output power at the first rate, and a currently set output power is increased at a third rate smaller than the second rate when the exhaust gas temperature reaches a forth set temperature smaller than the first set temperature after decreasing the set output power at the second rate.