PURPOSE: To accurately separate a horizontal synchronizing signal and a vertical synchronizing signal from a composite synchronizing signal with a different scanning frequency by obtaining a pulse width of a discrimination pulse corresponding to a pulse width of the composite synchronizing signal with revision of a count setting number.

CONSTITUTION: A horizontal synchronizing signal Hs and a vertical synchronizing signal Vs are separated from a composite synchronizing signal Cs separated by a video signal separator circuit 4 at a synchronizing separator circuit 5' and both the synchronizing signals are given to an A/D converter circuit 6 for A/D conversion. A timing generating circuit 8 gives a sampling timer clock Ck for forming a pulse and a selection signal Ss2 to select the width of the pulse being a reference of separation to the synchronizing separator circuit 5'. Moreover, when a composite video signal Cv with a different frequency is received by the circuit 4, an external selection signal Ss1 is given to the timing generating circuit 8 externally to change timing signals T1-T3 so that the circuit copes with the different frequency. Thus, the vertical synchronizing signal is accurately separated from the composite synchronizing signal with a different scanning frequency.