To obtain a quick motion vector search and a memory access reduction in an image information coding device based on an image coding method like AVC.

When searching a motion vector based on a layer search by specifying one of reference frame images per motion compensation block divided from a frame image for processing, the thinning device 12 reduces the pixels of the motion compensation block of the largest pixel size from the motion compensation block pixel size to create a small image in the lower layer, the reference frame decision device 15 decides a small reference image in the lower layer at a specified reduction ratio, the motion prediction compensation device (1/N2 resolution) 14 searches the motion vector using the created reduced image, and the motion prediction compensation device (full resolution) 17 searches the motion vector and predicts the motion using the specified search area by the motion vector searched for the image before it is reduced.