The treatment portion of the ultrasonic probe has a through hole penetrating from a first outer surface to a second outer surface facing away from the first outer surface, or a recess recessed in the first outer surface. . The treatment portion is a blade formed along the edge of the opening at the first outer surface of the through hole or the recess, and the blade in a state of facing away from the central axis of the through hole or the recess And an outer relay surface extending from the second outer surface to the second outer surface. The distance from the central axis of the through hole or the recess to the outer relay surface is kept equal to or less than the reference distance from the central axis to the blade over the range from the blade to the second outer surface Be超音波プローブの処置部は、第１の外表面から前記第１の外表面とは反対側を向く第２の外表面まで貫通する貫通孔、又は、前記第１の外表面において凹む凹部を有する。前記処置部は、前記貫通孔又は前記凹部の前記第１の外表面での開口の縁に沿って形成される刃と、前記貫通孔又は前記凹部の中心軸から離れる側を向く状態で前記刃から前記第２の外表面まで延設される外側中継面と、を備える。前記貫通孔又は前記凹部の前記中心軸から前記外側中継面までの距離は、前記刃から前記第２の外表面までの範囲に渡って、前記中心軸から前記刃までの基準距離以下に保たれる。
