An endoscopic treatment instrument is provided which includes: a sheath 2 having electrical insulating properties a pair of arm portions 3A and 3B which are disposed opposite to each other, which protrude and retract with respect to the sheath 2, and which accordingly open and close to thereby hold an object to be treated a cutting electrode 5 which is protruded from and fixed to the distal end of the sheath 2 and which supplies a high-frequency electric current when it touches the object to be treated.
