A valve body, e.g. a valve body adapted to be disposed in a connector to be connected to a catheter, has an opening/closing part which opens upon inserting a member into the opening/closing part and which closes upon withdrawing the member from the opening/closing part. The valve body includes a main body part made of a silicone rubber and a surface layer disposed on a surface of the main body part. This surface layer serves as a sliding surface which, when a guide wire has been inserted into the opening/closing part, slides on the guide wire. The surface layer is constituted mainly of silicon oxide and hence improves the sliding properties of the guide wire. Thus, the valve body is reduced in the resistance of sliding on the guide wire.
