The tool has a sheath inserted through a treatment tool guide lumen of an endoscope. A pair of electrode blades (14A, 14B) is disposed at front position of the sheath. The blades are adapted to open and close through remote manipulation of an operation unit. A planar portion (19) is provided at a tip of each blade such that each portion has a projected area larger than the cross sectional area of the blades at a portion close to the front end of the blades. A front support unit is connected to the front end of the sheath. An electrically insulating coating is attached to the tip of each blade.
