To strengthen strength of a valve by surrounding the whole faces of reinforcement with resin forming a valve body, and integratedly burying the reinforcement in the valve body, on the part position where the valve is apt to be broken and deformed, when a load is applied to the valve body made of a resin from the outside.

In this ball valve 3, a valve element 31 is rotatably mounted in a valve body 2, and a metallic handle receiving part 32 is provided on the extreme end of the stem 31a of the valve element 31 so as to project from the valve body 2. A seal ring 4 is internally provided in the valve body 2. A reinforcement formed out of metal material such as stainless steel, is provided with a trumpet-shaped pipe part 52 gradually spreading on one end of a straight pipe part 51. The reinforcement 5a surrounds the female screw 22 formed part of a socket from the outside with the straight pipe part 51, surrounds the valve element 31 part of the valve body 2 from the outside with the trumpet-shaped pipe part 52, and it is buried in the valve body 2, so that it is perfectly isolated from the outside with resin constituting the valve body 2.