Two-shaft gas turbine

A two-shaft gas turbine is provided which includes: a compressor; a combustor having multiple fuel systems and generating combustion gas by combusting fuels from the fuel systems and air compressed by the compressor; a high-pressure turbine coupled coaxially with the compressor and rotated by the combustion gas; a low-pressure turbine having a shaft structure independent of the high-pressure turbine and rotated by exhaust gas from the high-pressure turbine; an air extraction channel for extracting the air compressed by the compressor; an injection flow channel for feeding the air extracted through the air extraction channel back to the combustor; and a controller for controlling the flow rate of the fuel supplied to each of the fuel systems based on the air flow rate of the compressor, on the flow rate of the fuel supplied to the combustor, and on the temperature of the air in the injection flow channel.