Abstract: A network control system includes a managing device, separate devices that communicate with the managing device, and a repeater that interconnects the managing device and separate devices. In the network control system, when the managing device performs maintenance, the separate devices each include a separate device side power source control circuit. The power source control circuit controls the on-state and off-state levels of a power source which is to be delivered to a circuit including at least an activating signal monitor unit such as a separate device side wake-up packet monitor unit that monitors whether or not an activating signal such as a wake-up packet sent from tho managing device via the repeater has been received. When the power source control circuit detects that the power source switch of the separate device is in off-state, the power source control circuit suppresses the transmission of a predetermined signal to the repeater.