1. A video predictive decoding device comprising: a decoding unit which decodes a compressed data out of plural sets of compressed data obtained by encoding a plurality of divided regions, the compressed data comprising side information and a residual signal of a target region, which is a target to be decoded; a motion information reconstruction unit which reconstructs a motion vector used to generate a predicted signal of the target region from the side information; a motion information storage which stores the motion vector; a motion compensation unit which generates the predicted signal of the target region, based on the motion vector; a residual signal reconstruction unit which reconstructs a reproduced residual signal of the target region from the compressed data comprising the residual signal; and a picture storing unit which adds the predicted signal to the reproduced residual signal to reconstruct a pixel signal of the target region, and which stores the reconstructed pixel signal as a previously-reproduced picture, wherein the decoding unit decodes zero-th side information and first side information, wherein the zero-th side information contains a zero-th motion vector difference, and a zero-th motion vector predictor index used to identify as a zero-th motion vector predictor one motion vector selected from a plurality of motion vectors stored in the motion information storage, wherein the first side information contains a first motion vector predictor index used to identify as a first motion vector predictor one motion vector selected from a plurality of motion vectors stored in the motion information storage, wherein the motion information reconstruction unit comprises: a zero-th motion information reconstruction unit, which generates the zero-th motion vector predictor based on the zero-th motion vector predictor index, and which adds the generated zero-th motion vector predictor to the zero-th motion vector difference to reconstruct a zero-th motion vector; and a first motion information reconstruction unit, which generates the first motion vector predictor based on the first motion vector predictor index to reconstruct the generated first motion vector predictor as a first motion vector, wherein the motion compensation unit combines two signals obtained from the previously-reproduced picture, based on the zero-th motion vector and the first motion vector, to generate the predicted signal of the target region, wherein the decoding unit is configured to further decode indication information to indicate whether the first side information contains a motion vector difference, in each frame or in each slice, and when the indication information indicates that the first side information does not contain the first motion vector difference, the first motion information reconstruction unit is configured to generate the first motion vector predictor based on the first motion vector predictor index, and reconstruct the generated first motion vector predictor as the first motion vector.