A treatment instrument for an endoscope includes: an operation portion a cylindrical sheath that is connected to the operation portion and that also comprises an insertion portion an axial electrode that is protruded from and retracted into a distal end opening portion of the sheath by an operation of the operation portion and a distal end electrode portion that is provided at a distal end portion of the axial electrode wherein a tapered portion is formed at a distal end portion of the sheath, the tapered portion being in a tapered shape that a distal end side of the distal end portion is narrower than a proximal end side of the distal end portion.
