PURPOSE: To make forgery and alteration difficult by constituting a magnetic recording layer of ≥2 kinds of magnetic materials having different Curie points and coercive forces and recording preencoded magnetic data while heating the magnetic material having the lower Curie point at the time of constituting the magnetic recording medium of a substrate and the recording layer.

CONSTITUTION: The magnetic recording medium 1 is composed of the substrate 2 and the magnetic recording layer 3. The recording layer 3 is composed of two layers; the first magnetic recording layer 3a existing on the substrate 2 side and the second magnetic recording layer 3b disposed thereon. The magnetic materials included in the recording layers 3a and 3b are previously provided with the Curie points and high coercive forces varying from each other at this time. Nylon, etc., are used for the substrate 2 by taking heat resistance, strength and light nontransmittability into consideration. One of the recording layers 3a, 3b is provided with the higher coercive force and lower Curie point than the coercive force and Curie point of the other. The preencoded magnetic data are recorded there. The recording layer 3b is provided with the low coercive force and the high Curie point when the recording layer 3a constituted in such a manner has the high coercive force and the low Curie point. The recording layer having the low Curie point is heated at a low temp.