1. A moving picture encoding apparatus for dividing a target frame in a moving picture signal consisting of a temporal series of frames, into a plurality of target regions, detecting motion vectors for each of the plurality of target regions with reference to adjacent regions adjacent to a respective target region, each of the adjacent regions having a respective motion vector calculated relative to a frame different from the target frame, and performing coding based on motion compensation, the moving picture encoding apparatus comprising: means for selecting a plurality of adjacent regions adjacent to the respective target region and for identifying a motion vector of each of the selected adjacent regions; means for determining an optimum predicted motion vector as the motion vector of one of the selected adjacent regions; and means for correcting scaling of the determined optimum predicted motion vector based on all of a target reference frame referred to for detecting a motion vector of the target region, the target frame, and an adjacent reference frame referred to for detecting the motion vector of the one of the selected adjacent regions whose motion vector was used to determine the optimum predicted motion vector, wherein the means for selecting refers to a first adjacent reference frame to identify the motion vector of at least one of the selected adjacent regions and refers to a second adjacent reference frame different from the first adjacent reference frame to identify the motion vector of at least another one of the selected adjacent regions.