A network access control system includes an information device that has access to a relay device which relays communication in a communication network, by the use of access information, and performs communication via the relay device, and a management unit that finds information devices, wherein when the found information device has no access to the relay device and is a second information device which is allowed to have access to the relay device by a first information device, the management unit transmits the access information to the second information device without a request for authentication.