A connector functioning as an endoscope connector includes an outer cylinder member, an inner cylinder member, and an urging member. The outer cylinder member includes a channel, an inner circumferential section provided in an inner circumference of the channel, and an inner circumferential section provided further on the outflow port side than the inner circumferential section. The inner cylinder member includes an advancing/retracting section disposed to be capable of advancing and retracting along the channel and having an outer diameter smaller than an outer diameter of the inner circumferential section, an O-shaped ring disposed in an outer circumference of the advancing/retracting section and configured to fill a gap between the advancing/retracting section and the inner circumferential section when the advancing/retracting section is disposed in the inner circumferential section, and a through-path that pierces through the advancing/retracting section along the channel.
