A ticket image (trigger information), an imprint image, and special information (related information) are preliminarily stored in a computer including a touch panel. First, the ticket image is displayed on the touch panel. Then, when a stamp device is placed on the touch panel, the imprint image is displayed on the ticket image in an overlapped manner. Therefore, an intrinsic purpose of the stamp device is achieved. From this state, an icon is further displayed in the imprint image. When the icon is selected, the special information is outputted. As described, pressing a stamp with the stamp device is a necessary condition for outputting the special information, thus a “key” function for providing information is added to the stamp device.