Endoscope and attaching method of connection mouth ring to end of endoscopic flexible tube

1. An endoscope comprising: a flexible tube having a helical tube in which a thin strip plate is helically wound, a braid tube covering an outside of the helical tube, and a flexible outer tube covering an outside of the braid tube;

a connection mouth ring plastically deformed and fixed to an end of the flexible tube;

and a helical tube displacement preventing portion which is configured to prevent displacement of the strip plate of the helical tube at the end of the flexible tube to which the connection mouth ring is fixed, when the connection mouth ring is fixed to the end of the flexible tube, wherein at the end of the flexible tube to which the connection mouth ring is fixed, the helical tube displacement preventing portion places axially adjacent edges of the strip plate of the helical tube in close contact with each other, and places an end of the helical tube in collision with the connection mouth ring, wherein the connection mouth ring includes an inner mouth ring disposed inside the end of the flexible tube, and an outer mouth ring disposed outside the end of the flexible tube, and the helical tube displacement preventing portion fixes the helical tube to the outside of the inner mouth ring to prevent the displacement of the helical tube.

2. The endoscope according to claim 1 , wherein the helical tube displacement preventing portion includes, in the inner mouth ring, a collision portion with which the end of the helical tube is brought into collision.

3. The endoscope according to claim 1 , wherein the helical tube displacement preventing portion includes, on the outer periphery of the inner mouth ring, a groove portion into which the strip plate of the helical tube is fitted.