An ultrasonic probe for treating a shoulder joint includes a probe main body extending along a longitudinal axis, and the probe main body when a certain direction intersecting the longitudinal axis is a first intersecting direction. A curved extending portion that extends in a state of being curved toward the first intersecting direction with respect to the portion. The curved extending portion has a second intersecting direction when a first curved outer surface facing the first intersecting direction and a direction opposite to the first intersecting direction is a second intersecting direction. And an acute angle with respect to the longitudinal axis direction of the tangent at the tip of the second curved outer surface is 20 ° or more and 25 ° or less.肩関節を処置するための超音波プローブは、長手軸に沿って延設されるプローブ本体部と、前記長手軸に交差するある１つの方向を第１の交差方向とした場合に、前記プローブ本体部に対して第１の交差方向側へ湾曲する状態で延設される湾曲延設部と、を備える。前記湾曲延設部は、前記第１の交差方向側を向く第１の湾曲外表面と、前記第１の交差方向とは反対方向を第２の交差方向とした場合に、第２の交差方向側を向く第２の湾曲外表面とを備え、前記第２の湾曲外表面の先端での接線の長手軸方向に対する鋭角が２０°以上２５°以下となる。
