PURPOSE: To produce a highly reliable identification card which is hardly affected by defective contact and magnetism by generating an identification signal in accordance with presence or absence of shields buried in the card.

CONSTITUTION: In case magnetic shields 2 and 3 are buried in positions A and D out of positions AWD in a card body 1 and are read by a reader, coils 11W14 are excited by an AC power source 15 to generate an alternating field. Though this alternating field is received by coils 21W24, only coils 22 and 24 generate an electromotive force because magnetic shields 2 and 3 exist, and this electromotive force is read by a reading circuit 25. The read digital signal is "0101".