120 forms an axial contact seal between the seal sleeve 180 and the rotor base portion 112 by sufficiently increasing the area of the seal surface 182 it is possible to remarkably decrease leakage of the second high pressure operation gas from the second high pressure section 127 to the surrounding environment since the first seal 132 is provided between two non rotating members unlike a case where the first seal 132 is provided between the rotating portion 52 and the stationary portion 50 it is possible to easily realize improved seal efficiency in addition since the lower end of the stator 108 is sealed by the stator bottom wall portion 179 it is possible to prevent the first high pressure working gas from leaking from the first high pressure section 126 to the surrounding environment the working gas sealing area 120 has a first diameter in the first high pressure section 126 and a second diameter in the second high pressure section 127 and the first diameter is smaller than the second diameter accordingly the length in the circumferential direction of the second seal 134 is shorter than the length in the circumferential direction of the first seal 132 by using the shorter seal in the higher pressure side it is possible.