(EN) According to the present invention, state information indicating a state of a vehicle is received from said vehicle, and the presence of a first vehicle entering an intersection and a second vehicle entering the intersection from a direction opposite that of the first vehicle is recognized on the basis of the received state information. On the basis of the state information, a determination is made that the first vehicle is advancing straight and that the second vehicle is turning in a direction that cuts across an oncoming lane. If it has been determined that the first vehicle is advancing straight and the second vehicle is turning in a direction that cuts across the oncoming lane, then the first vehicle and/or the second vehicle is alerted to the possibility of coming close to another vehicle. The determination involves determining, on the basis of the state information received from the first vehicle, that the first vehicle is advancing straight if it has been determined that a turn signal is not operating or that turning-off the turn signal was forgotten.
