PURPOSE: To accurately detect ghost, by picking up a front edge of a vertical synchronizing signal in a composite video signal, converting the output signal into a digital signal after waveform conversion and performing relative operation of the digital signals.

CONSTITUTION: A vertical synchronizing signal pickup circuit 5 picks up a small section including the front edge of a vertical synchronizing signal in a composite video signal introduced from a subtractor 2. The output is given to a differential circuit 6 to form a differential signal having a peak corresponding to the vertical synchronizing signal front edge and its ghost waveform. The output is stored in an RAM9 via a sampling circuit 7 and an A/D conversion circuit 8. A microprocessor 11 sequentially fetches data from the RAM9, performs correlation operation and detects the delay time of ghost component and amplitude information. A tap gain switching circuit 4 is operated with the output of the processor 11 to switch the tap gain of each stage of a transversal filter 1.