PURPOSE: To dispense with magnets for initialization and bias magnets on overwriting by specifying the relation of Curie temps. of first to third magnetic layers and specifying the stray magnetic fields of the second and third magnetic layers to the first magnetic layer.

CONSTITUTION: On a substrate 11, a first magnetic layer 12 having a magneto- optical effect, dielectric layer 13, antiparallel type second magnetic layer 14 having perpendicular magnetic anisotropy, and third magnetic layer 15 are successively formed. These three magnetic layers are formed to satisfy the relation Tc1<Tc2<Tc3, when Tc1, Tc2, and Tc3 are Curie temps. of the first, second and third magnetic layers 12, 14, 15 respectively, and relations Hd2Hd3 at room temp., Hd2>Hd3 at near Tc1 and Hd2<Hd3 at temp. from Tc2 to Tc3, when Hd2 and Hd3 are the stray magnetic fields of the second magnetic layer 14 and third magnetic layer 15, respectively, to the first magnetic layer 12. In this case, by varying the power of laser light 16 according to the informa tion data to be recorded on overwriting, magnetic recording according to the information data to be recorded can be performed by using changes of the stray magnetic fields. Thereby, no initialization magnet nor bias magnet is required.