PURPOSE: To surely identify mark areas even if there are flaws and to stably read data by forming all the mark areas in data areas arrayed in a matrix with the same codes.

CONSTITUTION: A stripe area 12 as a recording area is provided in the prescribed area on the surface of a card base 11, and plural reference lines 13 are provided at the same intervals in the longitudinal direction of the stripe 12. Optical data is digitally (0 or 1) divided into sectors (small data areas) 16 and recorded on each band 14. The data area 16 is composed of plural tracks 17. The mark areas (headers) 18 are added to the data areas 16. The mark areas 18 are made of five tracks 17 respectively, for instance, and all of them are recorded with the same codes (1, for instance). If a line sensor reads data, the continuous codes 1 are detected when it comes near to the mark areas 18. Therefore the mark areas can surely be identified.