Abstract: An electronic scanning ultrasonic diagnostic system comprising a probe having ultrasonic beam emitting surface, in which plural ultrasonic wave transducers are convexly arranged at equal distances, emitting desired sector scanning ultrasonic beams, a transmitting and receiving wave control circuit dividing transducers into optional and plural groups and repeatedly performing of transmitting and receiving action with ultrasonic directivities respectively different to each group, and supplying ultrasonic beam scanning signals to an image display section with an assumption that the respective extension lines of each sector scanning ultrasonic beams coincide with the center of the arc shape of the probe.