PURPOSE: To increase the degree of freedom of spatial position by storing code information in concentric belt which has proper width for a binary state, and converting the code information into a hologram to be a medium.

CONSTITUTION: Information necessary to identify an individual is coded in two states (binary) like a black and white pattern. Then, one state which represents one piece of information corresponds to concentric belts 17 having the proper width. Therefore, the same information is recorded at all positions at equal distance from the center 18 of the code information. This invention uses the medium on which the code information is converted into a hologram as an individual identification card to prevent the erasure of the code information by ambient magnetism, and the degree of freedom of spatial positions to a reader for the identification card is increased.