PROBLEM TO BE SOLVED: To provide a distal end structure of an oblique-viewing endoscope which can reduce such a risk that an adhesive for adhesion between an auxiliary frame for supporting a cover lens and a prism and a rear group lens barrel for supporting rear group lenses adhere to an emission plane of the prism, and which can be assembled in a short period of time without damaging the cover lens.SOLUTION: A distal end structure of an oblique-viewing endoscope includes: a rear group lens barrel inserted into a distal end optical element storage hole 21 which is formed on a slope 20 formed in a distal end hard part 19 rear group lenses 52 supported inside the rear group lens barrel an auxiliary frame inserted into the distal end optical element storage hole, having a cover lens storage hole 29 on a front surface, and provided with a pair of prism fixing arms a cover lens 40 fixed by being fitted in the cover lens storage hole and a prism 34 held between the pair of prism fixing arms. The auxiliary frame includes a fitting projection that is fitted into a front end opening of the rear group lens barrel and onto which an adhesive adhering to an inner peripheral surface of the front end opening is applied.
