Each of vehicles acquires its own position, and transmits an image of a nearby outside taken by an own camera and a piece of information of the own position. An information center communicatable wirelessly with the vehicles receives the images and the pieces of information of the vehicles' positions transmitted by the vehicles, and recognizes pieces of first character information appearing in the received images, respectively. Based on the received pieces of information of the vehicles' positions as well as at least either points of interest or areas stored as collection target information, the information center determines at least either points of interest or areas for the recognized pieces of first character information, respectively, and stores association information where the pieces of first character information are associated with the determined at least either points of interest or areas.