A steam valve has a tubular stop valve configured to move toward an upper/lower end side along a direction of an axis when the stop valve is opened/closed; and a valve main body accommodating the stop valve, wherein a base end portion including an end portion of the stop valve at the upper end side is accommodated in a first accommodation space formed in the valve main body, the base end portion has a plurality of inclination surfaces formed on an outer circumference of the base end portion which are inclined such that a distance from the axis to each of the plurality of inclination surfaces decreases toward the upper end side, and a plurality of contact surfaces are formed in the first accommodation space to come in contact with the plurality of inclination surfaces respectively when the stop valve moves toward the upper end side.