To provide a connector to an endoscope having observation window cleaning means and fluid injection means, so as to keep a cleaning liquid feeding mechanism removably connected to a connector in its universal cord and make it possible to feed injected liquid, which the cleaning liquid feeding mechanism is not provided with.

A liquid-path 42, an air-path 43, and an injection-path 44 each open in the end of the connector-side removable portion 40a of a piping connection adapter 40, and the liquid-path 42 and the air-path 43 each open in a supply-side removable portion 40b, wherein the injection-path 44 extends as the introduction-path 49a provided in injection means connection portion 49 connected with the side surface of an adapter body 41. In the connector-side piping connection portion 35 of an endoscope SB of B type, a gas-supplying passage 13, a liquid supplying passage 14 and an injection passage 25 are each connected to the connector-side removable portion 40a, and an air-piping portion 21b and a liquid-supplying-piping portion 21a of the cleaning liquid feeding mechanism 19 are each connected to the supply-side removable portion 40b. In addition, a liquid supplying pipe 53 is connected to the injection means connection portion 49.