A road network analysis system detects major changes in a road network based on probe information from a plurality of vehicles. The probe information is tabulated and the change in the amount of traffic is calculated for each road with a predetermined time interval. If a remarkable change in the amount of traffic is detected for a road before and after a specific baseline day, it is determined that a major change in the road network affecting the traffic has occurred in the vicinity of the road, and the road is specified as a change-related road. A path search may be performed between the endpoints of a plurality of change-related roads, and the searched paths that have the most overlap with the searched paths are selected so as to identify the change-related roads which are commonly affected by the same cause and the endpoints thereof.