At an extended function server side, user information is received, and a user authentication process is executed. When the authenticity is established, an extended function table is read out, and an extended function list is generated in correspondence with users, based on the extended function table. Then, determination is made as to whether there is an extended function list set in correspondence with a user When there is an extended function list set in correspondence with a user, the extended function list is transmitted. At the MFP side, the extended function list transmitted from the extended function server is received. Then, the received extended function list is registered.