Abstract: The present invention is a system for monitoring encrypted data and preventing the encrypted data from being decrypted in large quantities, the system comprising: an access control unit which stores information of a decryption; a crypto-unit which receives the information of the decryption from the access control unit and decrypts the encrypted data; a counter which counts the number of the process of the decryption processed by the crypto-unit; an event logger which stores the number of the process of the decryption counted by the counter; and a monitoring server which receives the information of the number of the decryption and displays it.