An endoscope includes a cylindrical member, a first outward flange including a first cutout, a projection projecting inward from an internal circumferential surface of a hole formed in a distal end portion of an insertion section of the endoscope, and capable of being engaged with the first cutout, an elastic member to urge the cylindrical member toward a bottom portion of the hole, and a projecting portion formed to project from the internal circumferential surface of the hole and including a surface facing the bottom portion of the hole.
