PURPOSE: To provide the motion detection circuit reducing undetection of motion of B-Y and R-Y signals being color signals and improving dot disturbance without increasing a memory capacity with respect to the motion detection circuit used for a motion adaptive Y/C separator.

CONSTITUTION: The detection circuit is provided with an offset subsampling clock generating circuit 13 and a clock therefrom is used to control write/read of a 0.5 frame memory 2 being a 2nd frame memory. Since write control is implemented by using an offset subsampling clock whose phase is inverted for each line, any of R-Y, B-Y color signals is alternately extracted from each line to halve the quantity of input information for the storage in the memory 2. Thus, the motion is accurately detected from a portion where only one of the R-Y, B-Y color signals is changed.