Abstract: A line changeover device for an endoscope, which changes over a line which is arranged in the endoscope, is arranged such that it comprises a cylinder and a piston which is fitted and inserted into the cylinder in a retractable manner, a seal member which is abutted against the cylinder for retaining at least one of water tightness and gas tightness with respect to the cylinder is fixedly provided on an outer periphery of the piston, and a strength reinforcement is provided on at least a part between an outer periphery of said seal member and an inner periphery thereof. The water tightness and the gas tightness within the cylinder are retained or held, and a sliding resistance of the piston is kept appropriately or adequately without the use of lubricating oil. Sliding ability between the cylinder and the piston at the time of operation is improved. Operability can be made fine or satisfactory.

Abstract: An endoscope system in accordance with the present invention comprises: an endoscope having an insertional part, operation unit, and connector unit set in array, and including channels that communicate with an opening formed in the distal section of the insertional part and an opening formed in the operation unit or connector unit; and at least one cleaning instrument having a flexible tube that can be connected to the opening formed in the operation unit or connector unit of the endoscope and that has the overall length thereof set to 30 cm or larger.