PURPOSE: To discriminate fields easily and accurately, by comparing the phases of vertical signal V with a synchronizing signals obtained from composite synchronizing signals and the phases of vertical synchronizing signals obtained by delaying for a prescribed time.

CONSTITUTION: A composite synchronizing signal (a) is extracted by separating an input picture synchronizing separator circuit 5. Then, a horizontal synchronizing signal (b) is separated by using a monostable multivibrator 6 from the composite synchronizing signal. After this, a vertical synchronizing signal (c) is formed by comparing the phases of the composite synchronizing signal (a) with the phases of the horizontal synchronizing signal (b) at a D-type FF7. On the other hand, another vertical synchronizing signal (e) is formed by giving the composite synchronizing signal (a) to a vertical synchronizing separator circuit 9 having a prescribed delay time. By comparing phases of vertical synchronizing signals (c) and (d) with the D-type FF8, signals of different levels are output depending on odd fields and even fields. In this way, field can be discriminated easily and accurately.