A control device includes a plurality of input ports to which electrical components are connected, a potential setting unit that sets the plurality of input ports to have any one of a first reference potential and a second reference potential different from the first reference potential, an ID specifying unit that specifies identification information of the control device based on a combination of electric potentials of the plurality of input ports, a storage unit that stores the specified identification information, and a control unit that controls the electrical component based on the specified identification information. In the control device, in a given case, the ID specifying unit prohibits the identification information specified at the start of the control device from being written into the storage unit for a prescribed time, and specifies the identification information again after the prescribed time and writes it into the storage unit.