A high frequency treatment instrument for an endoscope is provided. The high frequency treatment instrument is provided with an insulative flexible sheath, an operation wire inserted in the flexible sheath so as to be movable along an axial direction of the operation wire in the flexible sheath, and a hook-like electrode attached to a tip of the operation wire. The hook-like electrode includes a rod-like part which is elongated in parallel with the axial direction along a line shifted from an axis line of the operation wire, and a hook part elongated from the rod-like part to cross the axis line of the operation wire.