To amplify ultrasonic energy speed by providing an amplifier with a proximal part receiving ultrasonic energy and a distal part transmitting ultrasonic energy, permitting the distal part to be a hollow shape and actuating it as a transmission horn for amplifying energy speed at the time of transmitting ultrasonic energy.

An ultrasonic transducer 10 is provided with a power source 12 connected to a power generator with a connector 14 and a vertical stack 16 with a plurality of piezoelectric elements 18 is connected to the power source 12. The vertical stack 17 consisting of half-wavelength segments 15 is fitted to the vertical stack 16 and a tip 40 as the transmission horn is fitted to the distal end part of the stack 17. Then, small repeated displacement in the vertical stack 161 is amplified by energizing the connecting body of the vertical stack 16 and an end part block 13 by a resonance frequency, electric energy is transmitted to the transmission horn 40 in a shape with a deviation along the plurality of half-wavelength segments and ultrasonic energy wave is amplified in proportion to the reduction cross section area of the distal part 44.