A plurality of known markers is disposed in a specific district. A marker detection section detects the known markers existing in the image photographed by an image pickup device. A position/orientation relation calculation section identifies the detected known marker to calculate position and orientation relations between the identified known marker and the image pickup device. An associated information obtaining section obtains predetermined information associated with the identified known marker. An information processing section processes the obtained predetermined information based on the calculated position and orientation relations. A display device superimposes and displays the processed information on the photographed image. At least the image pickup device and display device are disposed in a portable information terminal, and the other sections are disposed in a server which can perform radio communication with the portable information terminal.