Abstract: A user terminal includes a common key storage part which stores a common key to a terminal-side storage unit. A PKG takes as input the common key, encrypts information using the common key inputted, and transmits the information encrypted, as encrypted information to a server. The server includes an encrypted information storage part which stores the encrypted information received from the PKG, to a server-side storage unit. The server includes an information transmitting part which transmits, upon reception of an information delivery request from the user terminal, the encrypted information stored in the server-side storage unit, to the user terminal. The user terminal includes a decrypting part which decrypts the encrypted information received, using the common key stored in the terminal-side storage unit, thereby acquiring information.