An ultrasonic imaging arrangement performs tentative scanning of ultrasound to the inside of a living body with delay time corresponding to average sonic velocity, calculates delay time error in a delay time error detecting circuit by using received signals from each channel to which delay control has been performed in a digital delay circuit, compares in a delay time comparing unit the calculated data with a plurality of delay time error data corresponding to various sonic velocities using sound velocity as the parameter stored before hand in a sound velocity-derived delay time error storing unit, selects among those sonic velocities the one matching the delay time error data with a sonic velocity selecting unit, and calculates the sonic velocity within the living body. The calculated sonic velocity is fed back to CPU, and the delay data on the delay applied in the ultrasonic scanning is provided to a delay circuit.