PURPOSE: To always obtain a good sector tomographic image, by finely adjusting the mounting angle of a transducer to a pedestal to perform control so as not to shift the direction of the ultrasonic beam emitted from the transducer.

CONSTITUTION: A pedestal 1 is formed into an almost triangular shape as a whole and mount holes 2 are formed to the respective surfaces forming an equal angle (120°) to each other of said pedestal 1. A transducer (ultrasonic vibrator) 3 is mounted to each mount hole 2 by a mount means so as to capable of finely adjusting a mount angle. That is, the transducer 3 is engaged with an fixed to the inside of a ring-shape support 4 and protruding parts 5 are formed to the outer periphery of the support 4 at plural places and screw insert holes 6 are formed to the protruding parts 5. Screws 9 inserted through the screw insert holes 6 are screwed in screw holes 8 to mount the support 4 and the transducer 3 to each mount hole 2 and the inclination of the support 4 and transducer 3 to the pedestal 1 can be finely adjusted.