PURPOSE: To send a transversal wave at right angles to the surface of a propagating body by arranging a storage body filled with fluid containing magnetic particles between an ultrasonic wave conversion element and the propagating body, and applying a magnetic field and improving the apparent viscosity of a sound wave transmission material.

CONSTITUTION: The sound wave transmission material 13 formed by charging the fluid 17 containing magnetic particles 16 in a bag body 15 made of, for example, synthetic resin is arranged between the ultrasonic wave conversion element 1 and propagation body 14. An electric signal is applied between electric terminals 9a and 9b of the ultrasonic wave conversion element 1 and the vibrator 3 generates the transversal wave of an ultrasonic wave. Then a current is supplied to a coil 12 to produce magnetic field 20 and then the magnetic particles 16 in the sound wave transmission material 13 form a mesh structure to increase the apparent viscosity of the sound wave transmission material 13, so the transversal wave 18 of the ultrasonic wave can be transmitted efficiently.