The disclosed technology is directed to an ultrasonic probe comprises a probe main portion configured to transmit ultrasonic vibration generated by an ultrasonic transducer. A treatment portion is configured on a distal side of the probe main portion along a longitudinal axis thereof. The treatment portion includes first direction surfaces disposed in a first direction intersecting the longitudinal axis and second direction surfaces that are adjacent to the first direction surfaces and are disposed in a second direction different from the first direction surfaces. The first direction surfaces further includes a plurality of surfaces formed into a staircase shape when being viewed from the treatment portion and one or more surfaces formed into a staircase shape when being viewed from a side opposed to the distal side of the treatment portion. The second direction surfaces further includes a plurality of surfaces formed into a staircase shape toward the distal side.