PURPOSE: To improve the reproducing characteristics resulting from the transfer effect and the magnetic Kerr effect and to improve the degree of freedom of a material, by dividing a magnetic substance layer into a magnetic substance layer of high permeability and a magnetic substance layer having large magnetic Kerr effect.

CONSTITUTION: A magnetic substance layer 11 having large longitudinal magnetic Kerr effect, a magnetic substance layer 12 of high permeability and a magnetic substance layer 13 of vertical magnetization are formed on a transparent base 10. In writing information, magnetization 20 is recorded on the film 13, magnetization 21 is transferred to the layer 12 with a shift of 1/2-bit correspondingly, and magnetization 22 reflected with the magnetization 21 is formed on the layer 11 with exchange interaction. The polarized light is collected on the layer 11, the polarized surface of the reflected light is rotated with the longitudinal magnetic Kerr effect according to the direction of the magnetization 22. In rotating the polarized surface by the Kerr rotating angle corresponding to the magnetization in the layer 11 at an analyzer 18, the strong and weak light change is obtained opposing to the direction of the magnetization 22 and a signal corresponding to the magnetization 20 is obtained by converting this change.