The present invention includes a flow guide (17) that is disposed in a space (15A) formed in a casing, on an outlet side of a diffuser (14), the flow guide including: a first guide surface (17a) that is disposed on a rotor side provided to a compressor and a gas turbine, and that delays turning of a flow direction of a compressed gas which has passed through the diffuser (14); and a second guide surface (17b) that is disposed outside the first guide surface (17a) and that turns the flow direction of the compressed gas which has passed through the diffuser (14).