PURPOSE: To prevent video information in pay television broadcast, etc., from being intercepted by non-contractor by subtracting a noise signal from a scrambled video signal with the aid of a signal subtracter and restoring a normal video.

CONSTITUTION: In terms of the same noise generator 15 as a scramble 11 at the broadcasting side, the same noise generation algorithm as that of the scamble 11 can be obtained with use of key data 16 owned by each contractor. A horizontal synchronizing signal used as a start signal of the noise generator 12 of the scramble 11 is detected from the video signal which is inputted from a disk scramble input terminal 400 and has been subjected to the scramble processing, and a noise signal is produced as the start signal of the generator 15. By substracting this noise signal from the scramble processed video signal supplied to the terminal 400 by means of a signal subtracter 5, the noise signal is restored to a normal video, which is outputted from a de-scramble output terminal 410.