A traffic control system sets a target value related to a travel state based on a correlation between a vehicle travel speed and a traffic volume, and controls multiple vehicles (CS) on a road in accordance with the target value as a common target value. The target value can be set based on a predicted traffic volume at a region (103) that is ahead of, in a vehicle travel direction, the multiple vehicles on the road. For example, the traffic control system sets, as the target value, a target speed or a target value of a parameter related to an inter-vehicle distance.