Pushing or pulling operation arranged on the side where the gripping part 7 extends on the outer peripheral side surface 6g provided in the insertion part 5, the endoscope operating part 6, the gripping part 7 and the endoscope operating part 6 A treatment instrument mounting portion A having a detachable finger grip 52 and a treatment instrument mounting portion A which is detachable, and a treatment instrument provided on the side where the gripping portion 7 extends on the outer peripheral side surface 6g of the endoscope operation portion 6. When the treatment instrument operation section 51 is mounted on the mounting section A, the finger placement section B is located on the proximal end side of the finger hook section 52 and on the distal end side of the grip section 7.挿入部5と、内視鏡操作部6と、把持部7と、内視鏡操作部6に設けられた、外周側面6gにおける把持部7が延出する側に配置される押し操作または引き操作が可能な指掛け部52を有する処置具操作部51が着脱自在な処置具装着部Aと、内視鏡操作部6の外周側面6gにおける把持部7が延出する側に設けられた、処置具装着部Aに処置具操作部51が装着されたときに、指掛け部52の基端側であって把持部7よりも先端側に位置する指配置部Bと、を具備する。