An endoscope comprising: an operation section having an operation section main body provided with an operating member, a holding part connected to the operation section main body and provided with a treatment tool lead-in port, and an extension part extending from the holding part toward a distal end side and provided on a distal end side of the treatment tool lead-in port; an insertion section that is provided on a distal end side of the extension part and that is inserted into a subject; a treatment tool erecting base provided at a distal end part of the insertion section; a movable member (96;242) that is provided at the extension part and is arranged to be exposed to outside of the extension part; an erecting operation wire (60;126) that is coupled to the treatment tool erecting base at a distal end side thereof, that is coupled to the movable member (96;242) at a proximal end side thereof, and that is pushed/pulled in accordance with a movement of the movable member (96;242) to move the treatment tool erecting base; and an attachment member (98,98A;212;234;244) that is provided at a proximal end of the erecting operation wire (60;126); wherein an engagement hole (174,174A;214) is provided in one of the movable member (96;242) and the attachment member (98,98A;212;234;244), and an engagement portion (176,176A;216;236) that is engaged with the engagement hole (174,174A;214) in an attachable/detachable manner is provided at the other one; characterised in that: the movable member (96, 242) moves in association with an operation of the operating member; the attachment member (98, 98A, 212, 234, 244) is engaged with the movable member (96, 242) in an attachable/detachable manner by a one-touch operation; and the engagement portion (176,176A;216;236) is provided with an elastic deformation portion that is elastically deformed and engaged with the engagement hole (174,174A;214). an operation section having an operation section main body provided with an operating member, a holding part connected to the operation section main body and provided with a treatment tool lead-in port, and an extension part extending from the holding part toward a distal end side and provided on a distal end side of the treatment tool lead-in port; an insertion section that is provided on a distal end side of the extension part and that is inserted into a subject; a treatment tool erecting base provided at a distal end part of the insertion section; a movable member (96;242) that is provided at the extension part and is arranged to be exposed to outside of the extension part; an erecting operation wire (60;126) that is coupled to the treatment tool erecting base at a distal end side thereof, that is coupled to the movable member (96;242) at a proximal end side thereof, and that is pushed/pulled in accordance with a movement of the movable member (96;242) to move the treatment tool erecting base; and an attachment member (98,98A;212;234;244) that is provided at a proximal end of the erecting operation wire (60;126); wherein an engagement hole (174,174A;214) is provided in one of the movable member (96;242) and the attachment member (98,98A;212;234;244), and an engagement portion (176,176A;216;236) that is engaged with the engagement hole (174,174A;214) in an attachable/detachable manner is provided at the other one; characterised in that: the movable member (96, 242) moves in association with an operation of the operating member; the attachment member (98, 98A, 212, 234, 244) is engaged with the movable member (96, 242) in an attachable/detachable manner by a one-touch operation; and the engagement portion (176,176A;216;236) is provided with an elastic deformation portion that is elastically deformed and engaged with the engagement hole (174,174A;214). the movable member (96, 242) moves in association with an operation of the operating member; the attachment member (98, 98A, 212, 234, 244) is engaged with the movable member (96, 242) in an attachable/detachable manner by a one-touch operation; and the engagement portion (176,176A;216;236) is provided with an elastic deformation portion that is elastically deformed and engaged with the engagement hole (174,174A;214).