1. An image predictive decoding method executed by a processor of an image predictive decoding device to implement, the method comprising: extracting encoded data of prediction information to indicate a prediction method to be used in prediction of a signal of a target region serving as a decoding target and encoded data of a residual signal, from compressed image data obtained by partitioning an image into a plurality of regions and encoding image data of the regions; restoring motion information based on the encoded data of prediction information, wherein the image predictive decoding device restores a prediction block partitioning type indicating a number of prediction regions obtained by sub-partitioning the target region, based on the encoded data of prediction information, wherein, when the prediction block partitioning type indicates that the target region includes a first prediction region and a second prediction region, the image predictive decoding device further decodes the encoded data of prediction information to restore a first merge identification information indicating whether or not to utilize candidates for motion information including either both decoded motion information associated with neighboring regions neighboring the first prediction region and motion information that indicates a zero vector or only the motion information that indicates a zero vector for generating a predicted signal of the first prediction region, wherein, when the first merge identification information indicates not to utilize the candidates for motion information, the image predictive decoding device further decodes the encoded data of prediction information to restore a first motion information utilized for generating the predicted signal of the first prediction region, wherein, when the first merge identification information indicates to utilize the candidates for motion information, the image predictive decoding device further decodes the encoded data of prediction information to restore a first selection information identifying the first motion information utilized for generating the predicted signal of the first prediction region based on the candidates for motion information and to restore the first motion information based on the first selection information, wherein, the image predictive decoding device further decodes the encoded data of prediction information to restore a second merge identification information indicating whether or not to utilize decoded motion information associated with neighboring regions neighboring the second prediction region for generating a predicted signal of the second prediction region, wherein, when the second merge identification information indicates not to utilize the decoded motion information, the image predictive decoding device further decodes the encoded data of prediction information to restore a second motion information utilized for generating the predicted signal of the second prediction region, and wherein, when the second merge identification information indicates to utilize the decoded motion information, the image predictive decoding device further decodes the encoded data of prediction information to restore a second selection information identifying the second motion information utilized for generating the predicted signal of the second prediction region based on candidate for the decoded motion information except the first motion information from among the decoded motion information associated with neighboring regions neighboring the second prediction region, and to restore the second motion information based on the second selection information; storing motion information included in restored prediction information; generating a predicted signal of each of the first and second prediction regions in the target region based on the restored first motion information and the restored second motion information; restoring a reconstructed residual signal of the target region based on the encoded data of the residual signal; and generating a restored pixel signal of the target region based on the predicted signal and the reconstructed residual signal and to store the restored pixel signal as the previously-reconstructed signal.