A novel diagnostic ultrasound apparatus has a plurality of ultrasound probes 1, delay means pairs 4 and 7 arranged respectively in the plurality of ultrasound probes to electronically delay the timings of transmissions or receptions of ultrasonic waves by the ultrasonic transducers, position/orientation detecting means 10 and delay control signal generating means for generating a delay control signal to control signal delays of the plurality of ultrasonic transducers of the plurality of ultrasound probes, using information acquired from the means 10. The delay control signal is input to the delay means to control the timings of transmission of ultrasonic waves to a target object of examination.