To provide a high frequency incision instrument for an endoscope continuously performing respective treatments of an incision, peeling and hemostasis without inserting/retracting a treatment instrument again in a treatment instrument insertion channel of an endoscope.

A high frequency electrode 3 is formed into a dimension preventing from projecting outward from an extension surface Y of the outer edge of the distal end of a sheath 1, and the high-frequency electrode 3 is formed with a planar portion 3a continued from a conductive rod 2 and formed in one side displaced from an extension line X of a central axis of the distal end of the sheath 1 and a hooked portion 3b laterally projectingly formed from the distal end of the planar portion 3a to displace from the extension line X of the central axis of the distal end of the sheath 1 in the opposite direction to the planar portion 3a.