A high-frequency electrosurgical treatment instrument for operations, includes a pair of forceps pieces, an insulating member, a transmission member, a manipulation rod member, a distal end cover member, a shaft member and a manipulation portion. The instrument, includes a flow channel portion formed between the manipulation rod member and the shaft member, the flow channel portion being disposed along a longitudinal direction of the manipulation rod member to allow liquid to flow； a groove portion that communicates with the flow channel portion to allow the liquid to flow from the flow channel portion； and an opening portion that communicates with the groove portion to supply the liquid near the proximal end portions of the pair of forceps pieces.
