Abstract: An information card and card system that eliminates forgery and illegal use of a card. The information card includes a memory that stores information data, which includes one of image data and acoustic data and contains inherent data that is embedded in the information data according to steganographic information hiding. The inherent data is data that authenticates a legitimacy of a card owner of the information card. The information card system include the information card and a data processing terminal for authenticating the owner of the card and/or the authenticity of the card itself.