INFORMATION RECORDING CARD, AND DEVICE FOR MONITORING USING FREQUENCY FOR THE SAME

PROBLEM TO BE SOLVED: To prevent the forgery of an information recording card such as a prepaid card or a stored fare ticket. SOLUTION: A substrate 4 is provided with a thermosensitive recording sheet 2 colored in a prescribed shape after plural preliminarily decided positions are successively irradiated with a laser beam to be used as using frequency, and a visible light beam shading film 3 laminated on the thermosensitive recording sheet 2 for shading a visible light beam made incident on the thermosensitive recording sheet 2. Thus, once the thermosensitive recording sheet 2 is colored by the irradiation with the laser beam, it can not be returned to the original color so that this card can be difficult to be forged. Also, the visible light beam shading film 3 is laminated on the thermosensitive recording sheet 2, and the exact using frequency can not visualized so that this card can be difficult to be forged. Moreover, the refractive index of a light or the like is changed by the visible light beam shading film 3 so that the forged card can be detected.