PURPOSE: To check a vibration in a valve element due to a fluid as well as to keep off any wear on a guide surface in contact with the valve element by situating a guide rib in a position yet nearer to one of the two guide surfaces, keeping apart from a virtual plane inclusive of a passage and a hole axial center.

CONSTITUTION: The peripheral surface of a valve element 1 is supported in three directions by a guide rib sliding surface 5 of a guide rib 4 at the upstream side and two guide surfaces 6, 7 installed in the inner surface of a storage part 3c at the downstream side, respectively. The guide rib sliding surface 5 and these guide surfaces 6, 7 are all extended in the axial direction of the valve element 1. As for these positional relations, when looking from a valve center surface inclusive of both axial centers of a passage 3a and a storage part 3b, a width center of the guide rib sliding surface 5 canes off the valve center surface, and the guide surfaces 6, 7 are arranged each in symmetrical positions with the valve center surface. Since the guide rib sliding surface 5 is eccentric to the right from the passage center, a left passage of the valve element 1 grows larger as far as a portion for the eccentricity, thus a fluid is made easy to flow and static pressure is reduced. Force of a static pressure difference between symmetrical passages works on the valve element 1 toward the left from the right, through which any possible vibration due to a turbulent flow is preventable.