VALVE DEVICE

PROBLEM TO BE SOLVED: To provide a valve device capable of suppressing self-excited vibrations generated on a valve body, by a simple structure.SOLUTION: A upstream channel 11 on a fluid inlet side and a downstream channel 12 on a fluid outlet side continues in directions of intersecting each other through a valve chamber 13. At an opening portion 11a of the upstream channel 11 of a partitioning wall 14 for defining the valve chamber 13, a valve box 10 provided with a valve seat 15 gradually increasing a diameter toward a down stream side, and an annular seal portion 21 capable of being seated in the valve seat 15 are provided. A valve body 20 capable of moving forward/backward to/from the valve seat 15 is provided. Exciting force reducing means for reducing exciting force applied from fluid F to the valve body 20 is provided. The exciting force reducing means is a separation promoting portion 23 for separating fluid flowing out from a space between the valve seat 15 and the annular seal portion 21 from the valve body 20. In the separation promoting portion 23, at least a part of an outer peripheral portion of the valve body 20 is made to have a smaller diameter than an end portion on the downstream side of the annular seal portion 21.