PROBLEM TO BE SOLVED: To realize a structure capable of advancing and retreating a treatment tool without releasing a hand for gripping a speculum insertion portion in a small size and at low cost. SOLUTION: An advancing / retreating assisting tool 20 of a treatment tool 14 used for an endoscope 10 has a substantially L-shaped rotating member 21 and a center of the treatment tool insertion port 12 in the vicinity of the treatment tool insertion port 12 of the endoscope 10. It has a rubber belt 22 as a support member that rotatably or rotatably supports the rotating member 21 at a position away from the shaft, and the rotating member 21 is an end portion of a first side 211 extending in a first direction. It is provided at the end of the treatment tool fixing portion 24 which can support the sheath of the treatment tool and the second side 212 extending in the second direction intersecting with the first direction, and the operator can operate the treatment tool. An operation input unit 23 for inputting is provided, and a predetermined rotation axis is provided in the vicinity of the connecting portion between the first side and the second side and is substantially orthogonal to the first side and the second side. It can be rotated or rotated within the angle range of. [Selection diagram] Fig. 1【課題】視鏡挿入部を把持する手を離さずに処置具の進退動作が可能な構成を、小型且つ低コストで実現する。【解決手段】内視鏡１０に用いられる処置具１４の進退補助具２０は、略Ｌ字状の回転部材２１と、内視鏡１０の処置具挿入口１２近傍において処置具挿入口１２の中心軸から離れた位置で、回転部材２１を回動可能または回転可能に支持する支持部材としてのゴムベルト２２と、を有し、回転部材２１は、第１の方向に延びる第１辺２１１の端部に設けられ、処置具のシースを支持可能な処置具固定部２４と、第１の方向に対して交差する第２の方向に延びる第２辺２１２の端部に設けられ、操作者が操作を入力するための操作入力部２３と、を有し、第１辺と第２辺との連結部分近傍に設けられて第１辺及び第２辺に対して略直交する回転軸を中心として、所定の角度範囲で回転または回動可能である。【選択図】図１
