An edge map generator/edge weighting coefficient generator performs edge detection for respective blocks that compose a moving image frame Ft, and calculates correlations between the edges of the respective blocks and those of neighboring blocks as edge weighting coefficients. A predictive vector candidate determination unit calculates a plurality of motion vector candidates for each block based on this edge weighting coefficient. Of these candidates, a motion vector detector obtains a candidate with a small evaluation value based on prediction errors and motion vector cost as a motion vector, thereby generating an interpolation frame Ft-0.5.