Abstract: A surgical treatment instrument includes an insertion portion including a longitudinal axis, an operation portion provided on one end side of the insertion portion, and a treatment portion provided on the other end side of the insertion portion and configured to treat a living tissue. The treatment portion includes a piezoelectric element configured to generate ultrasound and an ultrasound transmitting material configured to transmit the ultrasound generated by the piezoelectric element to the living tissue.

Abstract: An ultrasound vibration device includes a stacked transducer in which a plurality of piezoelectric substances and a plurality of electrode plates are stacked, an external shape of the stacked transducer being in a polygonal prism shape, insulators, a case main body housing the piezoelectric transducer and the insulators, a pressurizing member screwed and fastened to an opening portion of the case main body to pressurize and fix the stacked transducer and the insulators in the case main body, and a plurality of positioning member insertion sections into which a positioning member is inserted, the positioning member retaining the stacked transducer and the insulators in the polygonal prism shape and positioning the stacked transducer in a position where the stacked transducer is non-contact with an inner wall of the case main body and one ends of the insulators are in contact with the pressurizing member.