Spatio-temporal differentiation method is one of the most effective methods of determining the velocity of moving objects. However, the optical flow estimate takes long time so that real-time object tracking is difficult to realize. In this study, we evaluated consuming time of the optical flow estimation when calculating in parallel. The method of parallelization includes dividing input image into several region and assigning each region into each multi-core. Because spatio-temporal differentiation method is composed of a local calculation, it is compatible with the parallelization method of dividing image into section. We can use the commercial multi-core processors to accelerate the optical flow estimation. It was found feasible to accelerate the optical flow estimation by the method. Experimental result shows that the most suitable acceleration can be achieved when dividing calculation region into parts of the same number of the cores.