A communication system includes a multifunctional apparatus, an authentication information input device, an I/F converter, and a control server. The control server includes an authentication information input device driver for controlling the operation of the authentication information input device via the I/F converter over a network and a multifunctional apparatus control section for controlling operation of the multifunctional apparatus. The authentication information input device driver causes the authentication information input device to acquire authentication information from a user, and receives, via the network, the authentication information acquired by the authentication information input device. Moreover, in cases where an authenticating section of the control server performs an authentication process with use of the authentication information and authentication is completed successfully, the multifunctional apparatus control section permits the use of the multifunctional apparatus. This makes it possible to build a flexible authentication system.