PURPOSE: To reduce fluid loss by disposing plural stationary blades in the circumferential direction in a narrowing path portion and disposing moving blades in the circumferential direction at equal intervals in between the outlet of a radial flow nozzle and an intermediate pressure first stage stator blade.

CONSTITUTION: Steam flowing into intermediate pressure inlet path 10 flows into a radial flow nozzle 21 disposed in annular form in a narrowing portion 11 from outer periphery, then flows in radial direction within the nozzle 21 and flows in to an impeller 21. Steam which has acted on a moving blade 22a of the impeller 22 and so imparted driving force, is directed into axial direction along profile of the moving blade 2a and thus flows to an intermediate pressure cascade 6 from an intermediate pressure first stage stationary blade 12. In this case, the radial flow nozzle 21 and the impeller 22 form smooth throttle path, so that steam 20b is accelerated while faired and thus generates output in lowering o the pressure. Flow is then uniformed into circumferential direction in the lower course of the impeller 22, so that incidence onto the intermediate pressure stage stationary blade 12 becomes almost zero and thus cascade loss in the intermediate pressure stage stationary blade 12 is reduced.