A image reproducing device decodes a moving picture stream having been subjected to inter-picture prediction encoding with a reference image memory accessed. A decoding processor performs variable length decoding of the moving picture stream on a picture-by-picture basis, and outputs an encoding parameter. A traffic analyzer estimates traffic to the reference image memory on the picture-by-picture basis based on the output encoding parameters. A reference image compression controller determines a compression mode in storing a reference image in the reference image memory based on the estimated traffic.