Valve structure and valve device having same field of the invention

A tubular part 4 capable of slidably fitting inside a valve hole 1 is formed on a valve disc surface 3 a, which is a plane on the side of the surface of a valve disc 3, which constitutes a valve structure, to be in close contact with a valve seat 2. When the valve disc 3 is in the closed position, the whole tubular part 4 is within the valve hole. A clearance in the fitting between the tubular part 4 and the valve hole 1 can substantially shut off the flow of a fluid A 1. The tubular part 4 has an opening in a tip end face 4 a; a through-hole 5 is formed in the outer circumferential surface of the body thereof: and when the valve disc is moved from the closed position to the open position, the through-hole of the tubular part 4 enters the valve chest, whereby the valve hole communicates with the valve chest through the tubular part via the through-hole. As a result, the fluid does not directly hit the valve disc surface in the open position, and the deposition of substances on the valve disc surface can be suppressed.