A user apparatus connected to database apparatus via network comprises: unit that manages key information in order to encrypt and decrypt; storage unit that stores security configuration information of data and/or metadata; application response unit that determines whether or not encryption is necessary for database operation command, and if encryption is necessary, selects encryption algorithm corresponding to data and/or metadata, performs encryption, and transmits result to database control unit to cause database control unit to execute database operation, if encryption is not necessary, transmits database operation command to database control unit to cause database control unit to execute database operation, and receives processing result transmitted by database control unit, and if decryption or conversion of data and/or metadata of processing result is necessary, performs necessary decryption or conversion, and returns response to database operation command; and security configuration unit that configures security information of data stored in database.