A system using ultrasonic sensor was developed to track a moving target. In Part 1, new techniques for sharpening the ultrasonic beam and for electronically sweeping the axis of emission of the beam, and their theoretical bases were described. In Part 2, the outline of the system is described. The performance verified by experiments is as follows: The maximum trackable velocity of a moving object, at a distance of 1.2m from the ultrasonic sensor system, is 480 mm/sec. The measurement error in the position of a target moving with this maximum velocity is 91 mm.