Abstract: By utilizing a cell phone carried by a driver or a fellow passenger to exchange with a base station during talking (through polling during non-talking), position information of the cell phone is obtained. The position information is collected and gathered as probe data and by matching the data with road map data, traffic congestion information on roads is generated. Then, when a business car of a driver carrying a cell phone is not traveling in a range initially predicted, it is decided whether position data of the cell phone is suitable as probe information and accurate traffic congestion information is generated.