In the present invention, a control terminal device is provided with: a communication unit that communicates with a communication device by a direct connection or via a network; and a storage unit that stores a system management table which manages the communication device. When a communication device is registered in a communication system, the control terminal device sends a search message to the entire network. The communication device is provided with a communication unit that communicates with the control terminal device by a direct connection or via the network. If the communication device is connected to the network, the communication device determines whether the connection position thereof is the prescribed connection position, and if connected at the prescribed connection position, responds to the search message via the network. If connected to the network but not connected at the prescribed connection position, the communication device disconnects from the network, directlyconnects to the control terminal device to acquire information for connecting to the prescribed connection position, and then connects to the prescribed connection position and responds to the searchmessage via the network.