PURPOSE: To trace a desired copy object with easy constitution by detecting the distribution of a moving vector and judging and deciding the moving vector which is the most dominant.

CONSTITUTION: Digital video signals which are sequentially inputted are inputted to a moving vector detector 20 to which frame coordinate data (x1, y1) and (x2, y2) in a tracing vector detection circuit are supplied, and the moving vector MV is detected. A distribution detection circuit 27 detects the distribution of the moving vector in a detection area based on the detected result, the moving vector which is the most dominant is judged and decided in a judgement circuit 29, and tracing is executed based on the vector. Thus, the desired object can be traced with easy constitution.