High-speed recognition of the shape of a target object is indispensable for robot arms to perform various kinds of dexterous tasks in real time. In this paper, we propose a high-speed 3-D sensing system with active target-tracking. The system consists of a high-speed camera head and a high-speed projector, which are mounted on a two-axis active vision system. By measuring coded structured light projected by the projector, 3-D measurement at a rate of 500 fps is achieved. The measurement range was increased because of the active tracking, and the shape of the target was accurately observed even when it moved quickly.