A control device for an on-board device including an actuator is configured to: supply power to a first microprocessor and a first driver circuit from a first power source through a first power supply path; supply power to a second microprocessor and a second driver circuit from a second power source through a second power supply path; and use the first and second driver circuits to drive the actuator. In this control device, the negative electrodes of the first and second power sources are electrically connected to a common ground portion. Specifically, the first negative electrode of the first power source and the second negative electrode of the second power source are connected to the common ground portion respectively through independent first and second connector portions.