PURPOSE: To simplify a circuit scale and to prevent distortion in a quantization error by scrambling a TV video signal without conversion into a digital signal and transmitting the scrambled signal.

CONSTITUTION: The memory circuit 21 of a scrambling signal generator 2 at a transmission side stores vertical synchronizing signals and horizontal synchronizing signals and burst signals by the color frame of a TV video signal classifications and various kinds of video signals suitable for disturbing the video signal in advance and the generator 21 generates a scramble video signal S5 in response to a control signal C1 from a control signal generator 1. An adder circuit 4 adds the signal S5 to a TV video signal S2 to scramble the video signal. An attenuation circuit 5 sets a level of the scrambled video signal S3 to be a regular level and the resulting signal is sent. A scramble signal generator 7 at a reception side generates the same signal S9 as the scrambled video signal S5 at the transmission side. A subtractor circuit 4 applies a subtraction processing to the signals 7, S29 to descramble them to be a TV video signal S8.