1. A method of encoding and decoding motion picture comprising the steps of: dividing a middle frame at about the midpoint between a previous key frame and a succeeding key frame in chronological order into a large number of patch-like regions according to its textural characteristics; estimating forward and backward motion vectors based on the previous key frame and the succeeding key frame respectively for each of the region-divided patch images in the middle frame; evaluating the reliability of each of the estimated forward and backward motion vectors to encode information on the motion picture including information on the previous and succeeding key frames, the patch images in the middle frame, the forward and backward motion vectors, and the reliability of each of the vectors; decoding frames near the previous key frame by interpolating the forward motion vectors between the previous key frame and the patch images in the middle frame; decoding frames near the succeeding key frame by interpolating the backward motion vectors between the patch images in the middle frame and the succeeding key frame; and decoding frames between the previous key frame and the succeeding key frame by interpolating either of the motion vectors that has higher reliability to compensate for their motion.