1. An image predictive encoding device comprising: a processor; a region partitioning unit executable by the processor to partition an input image into a plurality of regions that include a target region serving as an encoding target; a prediction information estimation unit executable by the processor to sub-partition the target region into a plurality of prediction regions, determine a prediction block partitioning type for the target region, predict motion information from a previously-reconstructed signal for acquisition of each of a plurality of signals highly correlated with the respective prediction regions, and obtain prediction information containing the prediction block partitioning type and the motion information, the prediction block partitioning type indicating a number and region shapes of the prediction regions; a prediction information encoding unit executable by the processor to encode the prediction information associated with the target region; a predicted signal generation unit executable by the processor to generate a predicted signal of the target region based on the prediction information associated with the target region; a residual signal generation unit executable by the processor to generate a residual signal based on the predicted signal of the target region and a pixel signal of the target region; a residual signal encoding unit executable by the processor to encode the residual signal generated by the residual signal generation unit; a residual signal restoration unit executable by the processor to decode the encoded residual signal to generate a reconstructed residual signal; and a recording unit executable by the processor to add the predicted signal to the reconstructed residual signal to generate a restored pixel signal of the target region, and to store the restored pixel signal as the previously-reconstructed signal, wherein the prediction information encoding unit includes a prediction information storage means executable by the processor to store previously-encoded prediction information, and the prediction information encoding unit is further executable to encode the prediction block partitioning type of the target region and store the prediction block partitioning type into the prediction information storage means based on: the prediction information of a region neighboring the target region, a number of previously-encoded prediction regions in the target region, and the previously-encoded prediction information of the target region; the prediction information encoding unit further executable to select a candidate for motion information, the candidate for motion information for use in generation of a predicted signal of a target prediction region serving as a next prediction region, and the candidate for motion information selected from previously-encoded motion information of a region neighboring the target prediction region; the prediction information encoding unit further executable to encode, according to the number of candidates for the motion information selected, merging block information indicative of generation of the predicted signal of the target prediction region, or encode either one of the merging block information or the motion information, wherein the merging block information is encoded using the selected candidate for motion information and the motion information detected by the prediction information estimation unit; and the prediction information encoding unit further executable to store the motion information for use in generation of the predicted signal of the target prediction region into the prediction information storage means.