An ultrasonic apparatus for diagnosis and therapy is provided with plural ultrasound probes for generating ultrasound waves for phase shift, diagnosis, and therapy. A first control part causes phase shift in a nano droplet ultrasound contrast agent, while a second control part detects the phase shift of the nano droplet ultrasound contrast agent using ultrasound echo detected by an echo detection device. A difference calculation device calculates a difference of the detected phase shift over time, and a positioning device determines a target position where the difference is produced. A third control part is also provided for exposing a decided target area to the ultrasound waves for therapy.