PURPOSE: To surely prevent highly pressurized water from leaking as well as to facilitate the maintenance of a device by letting a pressing piece in a bent section which is provided for the inner circumferential section of a circular sealing member roughly in a J-shape, be brought in contact with the outer circumferential face of a spherical valve body.

CONSTITUTION: In a ball cock wherein a valve body 12 in a spherical shape is provided for a valve chamber 2 at the lower center of a valve main body 1, and an upper handle 8 is connected with the valve body 12 so that the valve is freely opened/closed, a circular sealing member 16 roughly in a J-shape is provided between the outside inner circumferential section 17 of the valve chamber 2 of the valve main body 1 and the flange side inner face 19. And a pressing piece in a bent section provided for the inner circumferential section of the sealing member is brought in contact with the outer circumferential face 23 of the spherical valve body 12. This permits the recessed section of the circular sealing member 16 to be pressed by highly pressurized water, thereby allowing the pressing piece of the sealing member 16 to press intensively the outer circumferential face 23 of the spherical valve body 12 so that leaks of highly pressurized water are positively prevented. In addition, there is no need for a particular installation member when the sealing member 16 is installed onto the valve main body 1, it can be installed in a simple manner, the maintenance of the member can thereby be facilitated.