PROBLEM TO BE SOLVED: To provide an endoscope in which the screw-in force (torque) applied repeatedly each time a treatment instrument (treatment instrument attachment) is mounted to a mouthpiece member is distributed to thereby prevent the destruction of a collar member supporting the mouthpiece member and also the trouble that the mouthpiece member rotates relative to the collar member.SOLUTION: A non-circular raised fitting part includes: a circular raised cylindrical surface formed of a portion of a cylindrical surface with the axis of a metallic mouthpiece member as its center and a plurality of raised detents projecting outward in a radial direction of an extension surface of the circular raised cylindrical surface in a region where the circular raised cylindrical surface is not present. A non-circular recessed fitting hole includes: a circular recessed cylindrical surface which is engaged with the circular raised cylindrical surface and a plurality of recessed detents which project outward in the radial direction of an extension surface of the circular recessed cylindrical surface and which are engaged with the raised detents.COPYRIGHT: (C)2016,JPO&INPIT【課題】口金部材に対して処置具(処置具アタッチメント)を装着する度に繰り返し掛けられるねじ込み圧力(トルク)を分散させて、口金部材を支持するカラー部材の破壊ひいては口金部材がカラー部材に対して相対回転する不具合を防止することができる内視鏡を得る。【解決手段】非円形凸嵌合部は、金属製の口金部材の軸線を中心とする円筒面の一部からなる円形凸筒状面と、この円形凸筒状面の不存在部分において円形凸筒状面の延長面の径方向外方に突出する複数の回り止め凸部とを有する。非円形凹嵌合孔は、円形凸筒状面に対応して互いに係合する円形凹筒状面と、複数の回り止め凸部に対応して互いに係合する円形凹筒状面の延長面の径方向外方に突出する複数の回り止め凹部とを有する。【選択図】図6
