To improve erosion resistance of a valve stem of a steam valve.

The steam valve is constructed containing, in a casing 1, a valve seat 3 having an opening 2, a valve element 5 disposed opposed to the opening 2, the valve stem 7 for moving the valve element 5 toward and away from the valve seat 3, and a gland casing 9, a cylindrical support member, slidably supporting the valve stem 7. Even when the valve element 5 opens or closes, the collision of solid particles entrained in steam flow with the valve stem 7 is avoided by inserting a cylindrical part 17 of the gland casing 9 into an annular groove part 25 disposed in the valve element 5, and setting an axial distance D1 of a hole 23 and an axial distance D2 of the cylindrical part 17 to more than a stroke D3 of the valve stem.