PURPOSE: To avoid problems, such as oscillation, position control, a break of a valve rod, and so on, by forming passages for conducting pressure in a valve element for closing a valve seat such that the passages communicate with a recess formed on an end of the valve element in the center and periphery of the recess.

CONSTITUTION: This steam control valve assembly 46 for controlling steam distribution by cooperation with a valve seat 12 has a valve element 54 with a circular recess 62 formed on a plug end 22b. A center longitudinal bore 26b of the valve element 54 communicates with the circular recess 62 through plural branch passages 64 and an axial passage 64a. An outer face of the valve element 54 and a circumferential rim 66 of the recess 62 define a tapered circumferential wall 68, while the passages 64 tangentially contact with the wall 68. Thereby, a mean representative pressure applied across the recess 62 is certainly introduced into a bore 26a to be conducted to a variable displacement chamber partitioned between a balanced piston end 50 and a valve guide.