Endoscopic surgical instrument

An endoscopic surgical instrument comprising:

• an insertion section configured to be inserted into a body cavity and comprising a tip end part, a base end part, and a central axis extending from the tip end part to the base end part in a longitudinal direction of the insertion section;
• a vein keeper arranged at the tip end part of the insertion section and configured to hold a blood vessel to be harvested;
• a surgical section arranged at the tip end part of the insertion section at a position shifted from the central axis in a radial direction of the insertion section and configured to cut off a side branch from between the blood vessel to be harvested and a wall portion in the body cavity;
• a first electrode disposed on a first surface of the surgical section that faces the vein keeper side;
• a second electrode and a third electrode which are disposed on a second surface of the surgical section, the second surface being an opposite surface to that of the first surface;
• and
• a switching section configured to switch to one of an incision mode in which the side branch is cut off by supplying a current to the first electrode and the second electrode from an electric energy supply source and a coagulation mode in which the wall portion in the body cavity is coagulated by supplying a current to the second electrode and the third electrode from the electric energy supply source.