An ultrasonic probe treating a shoulder joint includes a probe main body section extended along a longitudinal axis, and a curved extending section extended in a state of curving relative to the probe main body section toward a first intersecting direction side when a certain direction intersecting the longitudinal axis is defined as the first intersecting direction. The curved extending section includes a first curved outer surface facing the first intersecting direction side, and a second curved outer surface facing a second intersecting direction side when an opposite direction of the first intersecting direction is defined as the second intersecting direction. An acute angle of a tangent line at a distal end of the second curved outer surface relative to the longitudinal axis direction is 20° or more and 25° or less.
