An ultrasonic surgical instrument (1) comprises an ultrasonic transducer (12) producing ultrasonic vibration, a transmission member (30) connected to the ultrasonic transducer (12) at a proximal end, and transmitting ultrasonic vibration produced by the ultrasonic transducer (12) from the proximal end to the distal end, a sheath (20) in which the transmission member (30) is inserted, a procedural unit (31, 33, 42) provided to the distal end of the transmission member (30) so that it projects from the distal end of the sheath (20), and treating a surgical target portion using ultrasonic vibration transmitted from the transmission member (30), a procedural unit main body (31b, 33b, 42b) provided in the procedural unit (31, 33, 42), and treating the surgical target portion, a procedural member (21, 44) provided in the sheath (20) so that it projects from the distal end of the sheath (20) to treat the surgical target portion, and a procedural member main body (21a, 4.9a) provided at the distal end of the procedural member (21, 44) to treat the surgical target portion. In the ultrasonic surgical instrument (1), the procedural member main body (21a, 44a) overlaps with the procedural unit main body (31b, 33b, 42b), and thereby, the procedural member main body (21a, 44a) and the procedural unit main body (31b, 33b, 42b) treat the surgical target portion.
