To control a vehicle by performing communication with a communication target present in an area designated by a user.
In a transmitting vehicle, a front area of the transmitting vehicle is designated based on the designation of the user. A transmission telegraphic message including data indicating the designated area and an identification number of the transmitting vehicle is transmitted from the transmitting vehicle. In the other vehicle receiving this transmission telegraphic message, when the vehicle belongs to a communication area defined by the data indicating the designated area included in the transmission telegraphic message, a reply telegraphic message including information on the other vehicle is transmitted to the transmitting vehicle. Based on the information on the other vehicle, running speed of the transmitting vehicle is controlled.