PROBLEM TO BE SOLVED: To achieve both of a feeding (movement/retreat) operation of a medical catheter and a deflection operation of a distal end of a sheath by one hand.SOLUTION: There is provided a distal end movable sheath 1 which is inserted preliminary for guiding insertion of a medical catheter 8 into a body. The sheath 1 comprises: a tube 2 which has a lumen for guiding the catheter； a rotation operation part 31 provided in the proximal end of the tube； and a grip part 4 which rotatably supports the rotation operation part. The grip part comprises: a front member 43 which is provided on a distal end side of the rotation operation part and to which the proximal end of the tube is connected； and a rear member 44 which is provided on the proximal end side of the rotation operation part. A dimension A in an axial direction from a center of the rotation operation part to the proximal end of the rear member is smaller than a dimension B in the axial direction from a center of the rotation operation part to the distal end of the front member.SELECTED DRAWING: Figure 1【課題】医療用カテーテルの送り（進退）操作とシースの先端部の偏向操作とを一方の手で両立的に行い得るようにする。【解決手段】医療用カテーテル８の体内への挿入を案内するために先行して挿入される先端可動シース１である。シース１は、カテーテルを案内する内腔を有するチューブ２と、チューブの近位端に設けられる回転操作部３１と、回転操作部を回転可能に支持するグリップ部４とを有する。グリップ部は、回転操作部の遠位端側に設けられ、チューブの近位端が接続された前方部材４３と、回転操作部の近位端側に設けられる後方部材４４とを有する。回転操作部の中心から後方部材の近位端までの軸方向の寸法Ａが、回転操作部の中心から前方部材の遠位端までの軸方向の寸法Ｂよりも小さい。【選択図】図１
