To realize autonomous manipulators which work outdoors, 3-D vision sensors having capability of real-time processing, robustness against sunlight and compactness are required to measure objects and environments. In this paper, a simple real-time motion stereo vision is proposed, which utilizes direct calculation of the integrated gradient constraint equation for sequential images taken by a motion camera. The vision sensor can measure 3-D coordinates at every pixel without huge computation. The basic characteristics are investigated through indoor measuring experiments. The measuring accuracy of ± 10% in a range of 0.7-1.5 m and the estimated measuring time of 0.1 s for 512 pixels × 100 scanning lines are obtained. Then the performance of the proposed vision sensor is experimentally investigated under natural conditions including outdoors.