An encryption algorithm management system has a terminal unit and a center unit that have a common cipher-key to a ciphered encryption algorithm. The terminal unit includes a transmitter configured to transmit a demand to the center unit for obtaining an encrypted data needed for decrypting the ciphered encryption algorithm when the ciphered encryption algorithm is decrypted, and an encryption controller configured to renew the common cipher-key in case of receiving the encrypted data from the center unit in response to the demand, and to produce an encryption algorithm by decrypting the encrypted data with the renewed common cipher-key. The center unit includes a key controller configured to renew the common cipher-key so as to be identical with the renewed common cipher-key in case of receiving the demand from the transmitter and an encoder configured to produce the encrypted data by encrypting a cipher-key with the renewed common cipher-key and to transmit the encrypted data to the terminal unit.