Channel tube coupling structure for anti-pollution type endoscope

An outer sheath detachably attachable to an insertion portion of an endoscope to cover the insertion portion, the outer sheath comprising:

• at least two ports open at a tip end portion of the outer sheath;
• a channel tube extending from the tip end portion through a base end portion of the outer sheath to an exterior, the channel tube having at least two communication channels that respectively communicate with the ports;
• at least two side holes that respectively communicate with the communication channels, provided in a base end portion of the channel tube exposed to the exterior, and offset from each other in an axial direction of the channel tube.

An endoscope having an insertion portion to which an outer sheath having a channel tube can be detachably attached to cover the insertion portion, the endoscope comprising:

• a tube connector having a coupling hole configured to receive a base end portion of the channel tube;
• at least two communicating holes formed in the tube connector, and having respective openings open at an interior surface of the coupling hole, the openings being offset in an axial direction of the coupling hole;
• at least three sealing members that define sealing faces that protrude radially inwardly from the interior surface of the coupling hole, and being located so that each of the communicating holes is located between adjacent two of the three sealing members in the axial direction.