PURPOSE: To obtain a visually satisfactory even in the case of an undercodable block having a motion by subjecting the picture signal, which is decoded based on the motion vector of a block estimated based on the appearance condition of motion vectors, to signal processing.

CONSTITUTION: An interpolating circuit 112 uses motion vectors of blocks around the error block detected by a motion vector detecting circuit 111 to estimate the motion vector of the error block, and thereafter, the estimated motion vector of the error block is used to rewrite data of the error block stored in a second field memory 109 by picture data in a third field memory 110, thus interpolating the picture. The motion vector detecting circuit 111 uses frequencies in appearance of relative vectors as data indicating the appearance condition of motion vectors. Since the motion vector is detected based on the frequency in appearance of the relative address (motion vector) in the search window of each block, the precision of motion vector estimation is improved.