According to a copy protection method of the present invention, as for a component video signal which is composed of a luminance signal and two color-difference signals, copy inhibition information is superimposed upon a first color-difference signal and information indicating that the copy inhibition information is included in the first color-difference signal is superimposed upon a second color-difference signal. Or copy inhibition information is superimposed upon the luminance signal, a vertical blanking interval, or a horizontal blanking interval.Accordingly, it can be judged whether or not the video is capable of copying, without making the viewers conscious, whereby component video signals can be easily copy protected.