A control device includes a controller that controls a target device, and the controller includes a power supply controller, a detector, an obtainer, and a setting changer. The power supply controller shifts, when a port connected to another device via a cable comes into an unused state, a power supply mode to the target device and to the control device from a normal power supply mode into a power saving mode capable of receiving activation interruption. The obtainer obtains, when the detector detects the change in the mounting state of the cable, type information representing a type of the cable. The setting changer that changes setting of the cable in accordance with the type information obtained by the obtainer. This makes it possible to be surely restored to the normal power supply mode even when a cable is replaced with another type of cable in a power saving mode.