PURPOSE: To provide the magneto-optical recording disk having a high C/N by forming an amorphous layer consisting of a rare earth-transition metal, a dielectric layer and a reflection layer on a transparent polycarbonate substrate having a double refractive index of a prescribed value.

CONSTITUTION: This magneto-optical recording disk is constituted by forming the amorphous recording layer 2 consisting of the rare earth-transition metal on the transparent polycarbonate substrate 1, forming the dielectric layer and the reflection layer thereon and forming the surface protective layer 3 thereon. The absolute value of the double refractive index of the polycarbonate substrate 1 is ≤25nm when the double refractive index is measured at ordinary temp. by using an He-Ne laser of 632.82nm wavelength. The surface of the amorphous layer 2 is provided with the dielectric layer and the reflection layer (both are not shown in the figure). The C/N of the magneto-optical recording disk is increased to ≥29dB. As a result, the magneto-optical recording disk having the magneto-optical characteristics equal to or better than the magneto-optical characteristics of a substrate consisting of an inorg. material, such as glass, and having an excellent handling property and mass productivity, is obtd.