PURPOSE: To reduce cost by minimizing the number of transmitting-receiving circuits or delay elements by reducing the number of the ultrasonic vibrators connected to the transmitting-receiving circuit blocks connected to the delay elements in the vicinity of both terminals of a theoretical delay pattern as compared with the number of those connected in the vicinity of the central part of the theoretical delay pattern.

CONSTITUTION: The transmitting-receiving circuit blocks 402-404 constituting a transmitting-receiving circuit 40 are connected to the respective delay elements 301-303 constituting a delay circuit 30 and an ultrasonic vibrator block 601 composed of one ultrasonic vibrator is connected to the transmitting-receiving circuit block 401 and an ultrasonic vibrator block 602 composed of two ultrasonic vibrators is connected to the transmitting-receiving circuit block 403 and an ultrasonic vibrator block 603 consisting of three ultrasonic vibrators is connected to the transmitting-receiving circuit block 403 and an ultrasonic vibrator block 604 consisting of five ultrasonic vibrators is connected to the transmitting-receiving circuit block 404. Nine ultrasonic vibrators in total are connected to the transmitting-receiving circuit 40. An ultrasonic vibrator selection circuit 50 is possible in switching operation with respect to all of the ultrasonic vibrators constituting an ultrasonic probe 6.