An ultrasonic surgical instrument comprising: an ultrasonic transducer adapted for producing ultrasonic vibration; a transmission member connected to the ultrasonic transducer at a proximal end, and adapted for transmitting ultrasonic vibration produced by the ultrasonic transducer from the proximal end to the distal end; a sheath in which the transmission member is inserted; a procedural unit provided to the distal end of the transmission member so that it projects from the distal end of the sheath, the procedural unit (31, 33) being adapted for treating a surgical target portion using ultrasonic vibration transmitted from the transmission member; a procedural unit main body provided in the procedural unit, and adapted for treating the surgical target portion; a procedural member provided in the sheath so that it projects from the distal end of the sheath to treat the surgical target portion, the procedural member being a shearing member which slides along a longitudinal direction of the transmission member including the procedural unit and the procedural unit main body; and a procedural member main body provided at the distal end of the procedural member and adapted to treat the surgical target portion, wherein the procedural member main body is a shearing portion, and the procedural member is adapted to slide such that the procedural member main body (21 a) overlaps the procedural unit main body (31 b), thereby the procedural member main body and the procedural unit main body treat the surgical target portion by shearing. characterized in that the procedural unit has a loop shape in the longitudinal direction of the transmission member, the loop shape is formed with an opening which is configured to penetrate the procedural unit in a thickness direction thereof and in which the surgical target portion is to be placed, the procedural unit main body is formed at a desired inclined state relative to the longitudinal direction of the transmission member at the distal end of the longitudinal direction of the transmission member in the loop. an ultrasonic transducer adapted for producing ultrasonic vibration; a transmission member connected to the ultrasonic transducer at a proximal end, and adapted for transmitting ultrasonic vibration produced by the ultrasonic transducer from the proximal end to the distal end; a sheath in which the transmission member is inserted; a procedural unit provided to the distal end of the transmission member so that it projects from the distal end of the sheath, the procedural unit (31, 33) being adapted for treating a surgical target portion using ultrasonic vibration transmitted from the transmission member; a procedural unit main body provided in the procedural unit, and adapted for treating the surgical target portion; a procedural member provided in the sheath so that it projects from the distal end of the sheath to treat the surgical target portion, the procedural member being a shearing member which slides along a longitudinal direction of the transmission member including the procedural unit and the procedural unit main body; and a procedural member main body provided at the distal end of the procedural member and adapted to treat the surgical target portion, wherein the procedural member main body is a shearing portion,