An incision tool includes a sheath; a plurality of wires that are inserted through an internal space of the sheath, and that, as a result of a portion thereof being inserted through both first wire insertion through holes that are provided in a distal end portion of the sheath and second wire insertion through holes that are provided on the sheath distal end side of the first wire insertion through holes, are exposed on the outside of the sheath between the first wire insertion through holes and the second wire insertion through holes, and that receive high-frequency current; and an operating unit that is connected to a base end side of the wires and that adjusts the length of the exposed portions of the wires which are exposed on the outside of the sheath by moving forwards or backwards relatively to the sheath in the longitudinal direction of the wires.