A connector 41 functioning as an endoscope connector includes an outer cylinder member 51, an inner cylinder member 52, and an urging member 53. The outer cylinder member 51 includes an inflow port 61 to which an endoscope cleaning/disinfecting apparatus 1 is connected, an outflow port 62, a channel P, an inner circumferential section 63a provided in an inner circumference of the channel P, and an inner circumferential section 63b provided further on the outflow port 62 side than the inner circumferential section 63a and having an inner diameter larger than an inner diameter of the inner circumferential section 63a. The inner cylinder member 52 includes an advancing/retracting section 52a disposed to be capable of advancing and retracting along the channel P and having an outer diameter smaller than an outer diameter of the inner circumferential section 63b, an O-shaped ring 54 disposed in an outer circumference of the advancing/retracting section 52a and configured to fill a gap between the advancing/retracting section 52a and the inner circumferential section 63a when the advancing/retracting section 52a is disposed in the inner circumferential section 63a, and a through-path 65 that pierces through the advancing/retracting section 52a along the channel P.
