In a gas turbine, a plurality of blade ring parts each include a plurality of first cooling flow passages, a plurality of second cooling flow passages, and a return flow passage. The first cooling flow passages are disposed on the outer side in a radial direction centering on a rotation axis, extend in an axial direction, and are disposed aligned in an axial rotation direction. The second cooling flow passages are disposed on an inner side in the radial direction with respect to the first cooling flow passages, extend in the axial direction, and are disposed aligned in the axial rotation direction. The return flow passage connects end parts of each of the first cooling flow passages and the second cooling flow passages on the same side in the axial direction with each other.