PURPOSE: To prevent the omission of a motion detection without inviting the detection spread to a still picture part.

CONSTITUTION: A motion detection signal Δf to be outputted from a mixer circuit 8 is outputted via the serial circuit of a maximum value calculation part 16 and a minimum detection part 23. In the calculation parts 16 and 23, calculations are performed within a 3-dot x 3-line block. In the maximum value calculation part 16, the motion detection signal is elongated in horizontal and vertical directions and the omission of the motion detection can be prevented as the motion detection signal of a picture element under consideration is calculated by the values within the minimum value calculation part 23, when the surrounding motion detection signal is lower than the motion detection signal of the picture element under consideration, the detection spread to a still picture part generating in the calculation part 16 can be suppressed as the motion detection signal of the picture element under consideration is exchanged for the lower value. Thus, the omission of the motion detection can be prevented in a good condition without inviting the detection spread to a still picture part.