An encryption apparatus for encrypting input picture data with high secrecy and restoration against an error of encrypted data. An EXOR circuit calculates input picture data and a pseudo random sequence and obtains encrypted data. The obtained encrypted data are held in a first FF circuit. The first FF circuit is reset for each line. Counters count for each line or each frame and are reset for each frame or at the beginning of a program. An encryption device encrypts outputs of a second FF circuit that holds a fixed value, the counters and the first FF circuit with a key and generates a pseudo random sequence. A shift register divides the bit sequence. The EXOR circuit calculates the output of the shift register and the input picture data and obtains encrypted data. Since the encrypted output is fed back, data cannot be stolen using a successive input of the same data. In addition, since an encrypted output that is fed back is reset for each line, the encrypted output can be recovered from an error.