Endoscope

1. An endoscope comprising:

a tube having a single layer structure or a laminated structure comprising a plurality of layers;

a branching member that branches a tubular path in an endoscope operation section and has a tube connection section to which the tube is connected;

a channel locking member that sandwiches the tube with the tube connection section and thereby tightly fixes the tube to the branching member; and

a fastening member that presses and brings into close contact the tube sandwiched between the tube connection section of the branching member and the channel locking member,

wherein the channel locking member comprises an inner tapered portion that covers an outer circumference of the tube and an outer tapered portion formed on an exterior surface of the channel locking member, the outer tapered portion being in parallel with the inner tapered portion, the channel locking member having at least one flat surface, the flat surface being substantially parallel to a central axis of the channel locking member, and the at least one flat surface being formed on the exterior surface such that a cross-sectional shape of a surface orthogonal to a central axis of the channel locking member is formed in a shape of an imperfect circle.

2. The endoscope according to claim 1 , wherein the flat surface is formed on a notched portion formed by notching part of the tapered portion on the exterior surface.

3. The endoscope according to claim 2 , wherein the notched portion of the tapered portion of the channel locking member is formed at two mutually opposing locations of the exterior surface.

4. The endoscope according to claim 1 , further comprising a friction reducing member arranged on a contact surface of either one of the channel locking member and the fastening member, the channel locking member and the fastening member coming into contact with each other on the contact surface.

5. The endoscope according to claim 4 , wherein the friction reducing member is a ball bearing.