To include a cooling passage leading from a latter stage of a compressor, via an external cooler, to a hollow part provided in a load coupling that couples a rotor of the compressor and a rotor of a turbine to each other, and also leading from the hollow part to the latter stage of the compressor, and a centrifugal compressor that raises air pressure in the hollow part with rotation of the load coupling, in the hollow part. Therefore, pressure of the air in the hollow part is raised by the centrifugal compressor by using a centrifugal force resulting from the rotation of the load coupling at the time of operating the gas turbine. Cooled air flows from the hollow part to between compressor rotor blades and compressor vanes at the latter stage, and then flows into the hollow part, thereby enabling to efficiently reduce temperature in the hollow part.