PURPOSE: To simplify contact scanning and indirect scanning and to facilitate handling by detachably press-fitting and securing a bag packed with liquid having specified acoustic impedance to the ultrasonic wave transmitting and receiving surface of an ultrasonic vibrator.

CONSTITUTION: The surface of an ultrasonic vibrator 13 is coated 15, and L-section supports 16a, 16b are fastened to both sides in the longitudinal direction of an ultrasonic probe 11. A bag 17 made of soft material such as rubber is hermetically sealed with a fluid of which acoustic impedance is appropriate between that of the ultrasonic vibrator and that of the object being examined, for instance, water 18. And a hook-shaped supports 19a, 19b are provided in the longitudinal direction of the bag 17, which are to be engaged with said supports 16a, 16b. Therefore, according to the form of the surface of the object being examined, both contact scanning and indirect scanning may be performed easily