PURPOSE: To prevent the unjust use of a display card by displaying 'in use' on the display card, by internally mounting an element having a display and memory function, a rectifying circuit and at least two or more conductors to the display card to color or erase the display of said card.

CONSTITUTION: A display element 13 and rectifying circuits 16, 17 are internally mounted between the first and second layers 1, 2. The holes for the continuity with the fourth layer 4 are opened to the patterned conductors 6, 7 on the second layer 2 in part and the same holes for continuity are also opened to the third layer 3. The display element 13 is bonded and formed so as to be brought to the continuity state with the conductors 6, 7, 11, 12 patterned on the second and fourth layers 2, 4. By applying an alternating electric field to a display card on the coloring conductive side thereof so as to become almost vertical to the surfaces of the conductors 6, 11, the charge determined by the areas of said conductors and the intensity of the electric field flows through the rectifying circuit 16 to color the display element 13. Contrarily, by applying the alternating electric field so as to be almost vertical to the surfaces of the conductors 7, 12, the display element 13 is erased. The display element 13 is colored by the alternating electric field applying part mounted in a ticket examination machine to make the visual examination of tickets possible.