1. A moving picture decoding apparatus for dividing a frame image as a decoding target in a moving picture signal consisting of a temporal series of frame image signals, into a plurality of target regions, and utilizing difference information between a predicted motion vector and motion vectors for the respective target regions detected with reference to a plurality of frame images different from the frame image as the decoding target, to perform decoding based on motion compensation, the moving picture decoding apparatus comprising: circuitry configured to select one predicted motion vector from among motion vectors of adjacent regions adjacent to a target region; and after selecting the one predicted motion vector, correct a scale of the selected predicted motion vector based on a temporal relation among (i) an adjacent reference frame image referred for detecting a motion vector of the adjacent region, (ii) a target reference frame image used for detection of the motion vector of the target region, and (iii) a target frame image being the frame image as the decoding target, wherein at least two of the adjacent regions adjacent to the target region refer respectively to two different reference frame images for detecting the motion vectors of the adjacent regions, and wherein, when a prediction mode for the target region is a mode where the target region is vertically segmented into two segmented-regions, a motion vector of an adjacent region located upper-right of the target region is determined as a motion vector estimate for a right segmented-region of the two segmented-regions.