An endoscope system of the present invention makes it possible to pass a cleaning brush through all conduits, simplify cleaning, and perform disinfection such as sterilization by an autoclave. The system is an endoscope for controlling the opening/closing of various conduits by an solenoid valve unit, in which a conduit unit is removably set to the joint at the rear end of an operating portion and a conduit to be connected to various conduits at the main frame side is set to the conduit unit. Moreover, a second cable which is used separately from a first cable in which an electric-signal transmission line is set is provided for the conduit unit to lead said conduit to the solenoid-valve unit. Thereby, it is possible to separately clean the conduit unit by removing it from the main frame. Therefore, cleaning is simplified and the conduit unit can be sterilized by an autoclave or the like.