An endoscope includes an elongated insertion section which has a distal end portion and is inserted into a body cavity. The insertion section has a rigid portion body on the distal end portion. The rigid portion body has at least one mounting hole in which each of optical members of an observation optical system and an illumination optical system is mounted. A binding portion which mechanically restricts the optical member with respect to the rigid portion body is provided on at least a part of the boundary between the mounting hole and the optical member mounted in the mounting hole.