PURPOSE: To increase the speed of motion vector detection processing by controlling the size of a motion vector retrieval area adaptively corresponding to a position correlative evaluation result.

CONSTITUTION: The same phase correlative evaluation means 1 evaluates the correlation of the block pattern of a processing block position and a processing block in a reference frame, and outputs a correlative evaluation signal S1. A retrieval range control means 2 outputs a retrieval range control signal S2 calculated based on the signal S1. A motion retrieval means 3 evaluates the correlation with each block pattern in a retrieval area decided by the means 2 when the signal S2 is supplied, and retrieves a vector in accordance with the block pattern in which the maximum correlation is obtained, and outputs it as a motion vector signal S4. A retrieval interruption control means 4 interrupts motion vector retrieval processing when the signal S1 exists within a prescribed level range. An output means 5 outputs a supplied signal S4 as a detection signal S5.