When motion vector is searched based on hierarchical search by designating any one of reference images of plural frames used every respective motion blocks, which have reference images of plural frames and are obtained by dividing an object frame image to be processed among successive frame images, a thinning unit (12) is operative to thin pixels of the motion compensation block having the largest pixel size caused to be uppermost layer among pixel sizes of the motion compensation block to thereby generate a contracted image of lower layer having a predetermined contraction factor; a reference frame determination unit (15) is operative to determine a contracted reference image on the contracted image; a motion compensation prediction unit (1/N2 resolution) (15) is operative to search motion vector by using the contracted image thus generated to search; with respect to an image before contraction, motion compensation prediction unit (full resolution) (17) is operative to search motion vector and perform motion compensation prediction by using a predetermined retrieval range designated by motion vector which has been searched at the motion compensation prediction unit (1/N2 resolution) (15).