Ultrasonic horn

An ultrasonic horn, comprising:

• a vibrator configured to generate longitudinal vibration having a frequency in the ultrasonic band on the basis of a signal having a frequency in the ultrasonic band input from an oscillator;
• a vibration amplifying unit configured to amplify the longitudinal vibration while transmitting the longitudinal vibration from the vibrator,
• wherein the vibration amplifying unit has a plurality of surfaces and a rectangular shape in a side view;
• and
• a longitudinal-torsional vibration conversion slit unit configured to convert the longitudinal vibration into torsional vibration, wherein the longitudinal-torsional vibration conversion slit unit has slits formed in a groove-like shape on two of the plurality of surfaces opposite to each other,
• wherein the slits are formed obliquely relative to a transmitting direction of the longitudinal vibration, and inclined directions of the slits respectively formed on the two of the plurality of surfaces relative to the transmitting direction of the longitudinal vibration are opposite to each other,
• wherein the vibration amplifying unit has another two of the plurality of surfaces opposite to each other not provided with the slits,
• wherein the another two of the plurality of surfaces not provided with the slits are respectively connected with the vibrator and inclined relative to the transmitting direction of the longitudinal vibration constantly throughout a whole range from the vibrator to an end surface of the vibration amplifying unit away from the vibrator.