PROBLEM TO BE SOLVED: To provide a treatment instrument for an endoscope capable of inserting a guide wire into a guide wire lumen easily when a multi-lumen sheath is provided.SOLUTION: A treatment instrument includes a second sheath 12 in which a slit 12e for moving a guide wire into or out of a first lumen is formed, and a sheath holding part in which a guide wire insertion opening 20b having a slit 20c and a main opening 20d is formed. A first end part of the second sheath 12 is formed with a first side part cut surface 12g and a second side part cut surface 12h that intersect in the shape of X, an axial direction cut surface formed by cutting in parallel with a center axis O12 from an end surface 12k, an opening surrounded by the first side part cut surface 12g, the second side part cut surface 12h, and the axial direction cut surface, and communicated with the first lumen at a position overlapping with the main opening 20d, and a piece-like part.SELECTED DRAWING: Figure 10COPYRIGHT: (C)2017,JPO&INPIT【課題】内視鏡用処置具において、マルチルーメンシースを備える場合に、ガイドワイヤをガイドワイヤルーメンに容易に挿通することができるようにする。【解決手段】処置具は、第１ルーメンにガイドワイヤを出し入れ可能なスリット１２ｅが形成された第２シース１２と、スリット２０ｃと主開口２０ｄとを有するガイドワイヤ挿入用開口２０ｂが形成されたシース保持部と、を備え、第２シース１２の第１端部には、Ｘ字状に交差する第１の側部切り込み面１２ｇおよび第２の側部切り込み面１２ｈと、端面１２ｋから中心軸線Ｏ１２と平行に切り込んで形成された軸方向切り込み面と、第１の側部切り込み面１２ｇ、第２の側部切り込み面１２ｈ、および軸方向切り込み面で囲われ主開口２０ｄに重なる位置の第１ルーメンに連通する開口部と、片状部と、が形成される。【選択図】図１０
