A vehicle control system comprising: a driving control device that includes a first processor and controls a driving section at a vehicle; a control instructing device includes a second processor and controls the driving control device by giving instructions by communication to the driving control device; and a communication path connects a plurality of control devices, including the control instructing and the driving control devices, the plurality of control devices communicate with one another, wherein the vehicle control system is structured wherein the first and second processors respectively compare a communication period of communication with another control device via the communication path, and a reference period that is stored in advance, based on results of comparisons on the communication period and the reference period that have been carried out by the first processor and the second processor, the second processor judges that there is an attack on the communication path.