To provide a structure of an opening and closing valve provided with an operation detection mechanism of a valve element allowing direct and secure confirmation of opening and closing of the valve element, which grasps an opening and closing operation condition of the valve element and controls various operation conditions and an opening of the valve element securely.

In this opening and closing valve 10 constituted in such a way that the valve element 20 opening and closing a flow-in port 13 for fluid F advances into and retracts from a valve chest 12 having the flow-in port 13 and a flow-out port 14 for fluid F, an operation detection member 40 for detecting moving of a movable part 30 advancing and retracting integrally with the direction (a) of advance and retraction of the valve element 20 is provided. As for the operation detection member, a photoelectric sensor 40A for detecting moving of the movable part as changes of position and a load sensor 40B for detecting moving of the movable part as changes of load are provided as examples.