In an endoscope of the present invention, while a cover indicator on a distal cover is aligned with a scope indicator on a main distal part, the distal cover is put on the main distal part in an axial direction at a certain insertion angle. Thereafter, the distal cover is rotated while being thrust in the axial direction. The stoppage of a locking convex part of a hook of the main distal part by a claw of a reinforcement member is released, and the locking convex part of the hook is positioned in a locking ditch of the reinforcement member. The head of the hook is constrained to move in the axial direction by means of a main distal cover that is an elastic member and the claw. The locking convex part is then fitted into the locking ditch reliably. Consequently, the distal cover can be fixed to the main distal part readily, freely detachably, and reliably with high positioning precision.