PROBLEM TO BE SOLVED: To provide a treatment tool for an endoscope comprising an inner sheath in which two tubes having a rigidity different from an outer sheath are connected, in which operation failure in the treatment tool for an endoscope which may occur in a case where relative movement in the outer sheath and the inner sheath is no smooth is solved.SOLUTION: As an inner sheath 12 which is inserted into an outer sheath 14 and into which a driving wire in which an action part is attached on its tip is inserted, the tool comprises a tip tube 12a arranged at a tip end part and a main tube 12b in which the distal end of the tip tube is connected to the proximal end. The rigidity of the tip tube is designed to be smaller than that of the main tube. A small diameter part 12c having a smaller outer diameter than a section other than a predetermined section at the distal end of the main tube is used for the predetermined section of the main tube such that the rigidity of the predetermined section of the main tube is larger than that of the tip tube and smaller than that of a section other than the predetermined section of the main tube.SELECTED DRAWING: Figure 18COPYRIGHT: (C)2016,JPO&INPIT【課題】アウターシースと剛性の異なる２つのチューブが接続されてなるインナーシースとを備える内視鏡用処置具において、アウターシースとインナーシースとの相対移動がスムーズでない場合に生じうる内視鏡用処置具の動作不良を解決する。【解決手段】アウターシース１４に挿通され、その先端に動作部が取り付けられた駆動ワイヤが挿通されるインナーシース１２として、先端部に配置される先端チューブ１２ａおよび該先端チューブの近位端に遠位端が接続された本体チューブ１２ｂとを有し、先端チューブの剛性は本体チューブの剛性よりも小さい値に設定され、本体チューブの遠位端側の所定の区間を、当該所定の区間の剛性が先端チューブの剛性よりも大きく、本体チューブの当該所定の区間以外の区間の剛性よりも小さくなるように、本体チューブの当該所定の区間以外の区間よりも小さな外径を有する細径部１２ｃとしたものを用いる。【選択図】図１８
