Abstract: A master key generation device generates a master public key and a master secret key. A user key generation device generates a user public key and a user secret key by using the master public key. An administration device acquires an arithmetic procedure. A data save unit saves data encrypted with the user public key as encryption data. The administration device selects, from the data save unit, encryption data which has been encrypted from data to be used for the arithmetic procedure. The administration device performs homomorphic operation on the encryption data based on the arithmetic procedure, and outputs the operation result of the homomorphic operation as an encryption operation result. A master decryption device acquires the encryption operation result, and decrypts the acquired encryption operation result with the master secret key.