1. An image predictive encoding device comprising a processor and a memory that stores a program for programming the processor to: partition an input image into a plurality of regions including a target region to be encoded; sub-partition the target region into prediction blocks comprising a first prediction block and a second prediction block; construct prediction block partitioning type information indicating a number of the prediction blocks sub-partitioned in the target block; using a reconstructed image signal, estimate first and second sets of motion information, respectively, for use in acquiring a prediction signal correlated to the first prediction block and a prediction signal correlated to the second prediction block; construct prediction information for the target region including (i) the prediction block partitioning type information, (ii) the first set of motion information, (iii) the second set of motion information, (iv) first merge identification information indicating whether or not to utilize motion information associated with neighboring regions neighboring the first prediction block, when generating the prediction signal of the first prediction block, and (v) second merge identification information indicating whether or not to utilize motion information, except the first set of motion information, associated with neighboring regions neighboring the second prediction block, when generating the prediction signal of the second prediction block; encode the prediction information for the target region; generate the prediction signal of each of the first and second prediction blocks from the first set of motion information and the second set of motion information; derive a residual signal which is a difference between a pixel signal of the input image and the prediction signal of each of the first and second prediction blocks; encode the derived residual signals; decode the encoded residual signals to generate reconstructed residual signals; and generate a restored pixel signal of the target region from the prediction signals and the reconstructed residual signals and to store the restored pixel signal as the reconstructed image signal.