A control device is a control device that manages a network including a plurality of communication devices. The control device includes: a mode transition unit that makes transition to a leave mode for disconnecting a communication device from the network; an initialization-reset transmitting unit that transmits, when a notification is accepted from at least one communication device of the plurality of communication devices during the leave mode, an instruction for setting a flag and a reset order to the communication device from which the notification is accepted, the flag defining to bring the communication device back to an initial state; and a deleting unit that determines whether or not the instruction for setting the flag and the reset order are received and that deletes information about the communication device connected to the network when it is determined that the instruction for setting the flag and the reset order are received.