Endoscopic treatment tool of the present invention (1), the sheath (2), further having a predetermined thickness in the radially outward from the inner circumferential surface of the first hole (21) at the tip of the sheath (2) extension has a cylindrical extending distally (21a), passive electrode (30) is arranged by surrounding the outer periphery of the extension (21a). In accordance with the present invention, it is possible to ensure sufficient insulating properties with a simple structure during the high-frequency treatment portion which is arranged to (21) in the first hole and (50a) passive electrode (30).本発明の内視鏡用処置具(1)において、シース(2)が、シース(2)の先端において第一孔(21)の内周面から径方向外方に所定厚さを有しさらに先端側に延びる筒状の延長部(21a)を有し、受動電極(30)が、延長部(21a)の外周を囲繞して配置されている。本発明によれば、第一孔(21)内に配される高周波処置部(50a)と受動電極(30)との間において簡易な構成で十分な絶縁性を確保することができる。
