To provide a steam valve device for reducing a steam amount leaking from a clearance between a valve rod and a bush, and to provide steam turbine power generation facilities equipped therewith.

The steam valve device 10 includes a steam valve body having a steam inlet portion and a steam output portion, and an upper lid 30 for closing an upper face opening portion of the steam valve body. A valve seat is provided to the steam outlet side. A valve element for abutting on the valve seat is provided at the front end of the valve rod 26 passing through the upper lid 30 and inserted inside the steam valve body. On a portion of the valve rod 26 passing through the upper lid 30, the bush 31 is provided at a predetermined clearance between the valve rod 26 and itself so that the valve rod 26 can be moved forward and backward in the axial direction. Peripherally over the inner face of the bush 31, an air flow generator 50 is provided for changing steam flowing into the clearance between the valve rod 26 and the bush 31 into a plasma form to generate an air flow in the clearance between the valve rod 26 and the bush 31.