To provide an information detection system related to a mail order system for acquiring various information items by embedding a watermark image to photos and catalogues of articles used for mail order or the like and analyzing image information.

Watermark information is embedded, in particular URL information as electronic watermark information is embedded without fail to photos, catalogues, television images, moving pictures, and music or the like of articles, a camera-attached mobile phone is used to photograph e.g., the image, uses the URL information included in image data, connects with an opposite enterprise via the Internet, can simply place an order of article purchase and the opposite enterprise invites users and carries out information providing services or the like for the users.