The ultrasonic treatment instrument for articulations according to the embodiment of the present invention includes, at the distal end of the probe, the treatment section which performs a desired treatment on the treated target part. The treatment portion is provided with an edge which extends in a direction crossing, or a direction parallel to, the longitudinal direction of the probe; a first ultrasonic transducer which generates ultrasonic vibration in a direction crossing the edge; and a second ultrasonic transducer which generates ultrasonic vibration in a direction parallel, to the edge.