To restrain a substance included in a fluid from accumulating on at least a valve body surface.

A cylindrical section 4 is arranged on the valve body surface 3a at a side stuck on a valve seat 2 on the surface of a valve body 3 forming a valve structure by projecting so as to slidably get into a valve hole. When the valve body 3 is located on a closed position, the cylindrical section 4 enters the valve hole in whole, and a clearance of a fit between the cylindrical section 4 and valve hole 1 is provided to approximately block a flow of a fluid A1. An opening is arranged in the tip face 4a of the cylindrical section 4. When the valve body is moved from the closed position to an open position, a through-hole 5 of the cylindrical section 4 is entered into a valve chamber, and the valve hole and valve chamber can be connected with each other through the through-hole in the cylindrical section. Thus, the fluid does not directly strike the valve body surface in an open state of the valve body, and accumulation of the substance on the valve body surface can be restrained.

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