PURPOSE: To prevent the original picture from being stealthily recorded and reproduced through a VTR, by producing a composite video signal with addition of the disturbance signal haing the phase synchronization with the horizontal synchronous signal and reproducing a normal picture through a monitor picture receiver.

CONSTITUTION: The composite video signal supplied from a signal source 1 is applied to a mixer 3 and at the same time separated through a synchronous separating circuit 4. And the horizontal synchronous signal is applied t a monomulti 5. The monomulti 5 is triggered at a time point of fall of a horizontal synchronous pluse P1. Then a pluse P2 is applied to a monomulti 6, and the monomulti 6 is triggered at the fall of the pulse P2. Thus a pulse P3 of a prescribed duration is supplied to the mixer 3 via a locked oscillator 7. At the mixer 3, the wave oscillated from the oscillator 7 is applied to the area including at least the horizontal synchronous signal Ph during a horizontal blanking period of the video signal snd in the form of a disturbance signal P3. Under such conditions, the composite video signal is transmitted. This composite video signal can be reproduced in the form of a normal picture only through a monitor picture receiver.