PROBLEM TO BE SOLVED: To fix a fixture in close contact with a cylinder so that the fixture does not slip in the cavity of the cylinder when the wire rod is moved forward and backward by an operation handle on the hand side. A high-frequency treatment tool extends in the perspective direction, and has a cylinder 10 having at least a first cavity 11 and a second lumen 12, and a part in the perspective direction is exposed to the outside of the cylinder. , A metal wire rod 20 whose other portion is arranged in the first cavity 11, and a fixture 30 which is fixed to the distal end portion of the wire rod 20 and is in contact with the inner wall surface of the first cavity. The fixture has a first section 31 in which the cross-sectional area in the cross section perpendicular to the perspective direction decreases toward the distal side, and the first section is in the perspective direction, the distal portion, the central portion, and the like. When divided into three equal parts in the proximal part, the surface roughness of the proximal part of the first section is larger than the surface roughness of the distal part of the first section, and the roughness curve in the circumferential direction of the surface of the fixture. Is the arithmetic average roughness Ra between the reference lengths of, and the reference length is a quarter length of the circumferential length of the fixture at each measurement position. [Selection diagram] Fig. 3【課題】固定具を筒体に密着して固定し、手元側の操作ハンドルで線材を進退操作したときに筒体の内腔で固定具が滑らないように固定する。【解決手段】高周波処置具は、遠近方向に延在しており、少なくとも第１内腔１１と第２内腔１２を有する筒体１０と、遠近方向の一部が筒体の外側に露出し、他部が第１内腔１１に配置されている金属製の線材２０と、線材２０の遠位端部に固定され、第１内腔の内壁面と当接している固定具３０と、を有し、固定具は、遠近方向と垂直な断面における断面積が遠位側に向かって小さくなっている第１区間３１を有し、第１区間を遠近方向において、遠位部、中央部、近位部に三等分割したときに、第１区間の近位部の表面粗さは、第１区間の遠位部の表面粗さよりも大きく、かつ固定具の表面の周方向における粗さ曲線の基準長さ間での算術平均粗さＲａであり、基準長さは、各測定位置における固定具の周長の四分の一の長さである。【選択図】図３
