A blind spot identification unit (21) identifies a plurality of obstacles causing a blind spot in an area around a vehicle. An individual calculation part (231) calculates, as an individual probability, a probability of occurrence of a traffic accident at a target position with respect to the position of a target object which is each of the obstacles identified by the blind spot identification unit (21). A combined calculation part (232) calculates, as a combined probability, a probability of occurrence of a traffic accident at the target position with respect to each of the plurality of obstacles from the individual probability calculated by the individual calculation part (231).