In a vehicle control device in which a driver circuit which does not have a computing function and a computing device communicate with each other, there is provided a technology which can efficiently diagnose that both the driver circuit and the computing device normally communicate with each other by a simple technique. The vehicle control device according to the present invention transmits diagnosis data as a control command from a computing portion to the driver circuit, and the driver circuit sends inverted diagnosis data in which the diagnosis data is bit-inverted back to the computing portion. The computing portion diagnoses whether or not the communication between the computing portion and the driver circuit is normally performed, by using the diagnosis data and the inverted diagnosis data.