The channel sheath (1) has a proximal end member (2) having a first opening (2a) for inserting a treatment instrument and capable of being placed in a body surface, a channel sheath (1) capable of being connected to the proximal end member A tubular intermediate member (6) having flexibility and capable of inserting the treatment tool, and a second opening (8a) for allowing the treatment tool to protrude and retract, and is detachably attached to a medical instrument different from the treatment instrument And a distal end member (8) which is possible and connected to said intermediate member (6).チャンネルシース（１）は、処置具を挿通するための第一開口（２ａ）を有し体表に留置可能な近位端部材（２）と、前記近位端部材（２）に接続され可撓性を有し前記処置具を挿通可能な筒状の中間部材（６）と、前記処置具を突没させるための第二開口（８ａ）を有し前記処置具とは異なる医療器具に着脱可能であり前記中間部材（６）に接続された遠位端部材（８）と、を備える。
