To provide an insertion part of an endoscope for reliably preventing water leakage from a joint part between an insertion part flexible tube and a bending part joined to its tip.

In an insertion part of an endoscope where on a flexible tube outer skin 13, a slope surface 13a which faces a diagonal front outside in adjacency just behind a back end surface 24a of the bending part outer skin 24 is formed, and adhesive 42 is filled in and fixed in a space 41 of a gap between the back end surface 24a of the bend part outer skin 24 and a slope surface 13a of the flexible tube outer skin 13, the slope surface 13a formed on the flexible tube outer skin 13 is a rough surface formed by grinder working.