A magneto-optical disk of the present invention includes a substrate and a recording layer disposed above the substrate, and reproduces an information signal by a DWDD system, using light incident from the substrate side. The optical disk further includes a first dielectric layer disposed between the substrate and the recording layer and a second dielectric layer disposed on the recording layer opposite to the substrate, wherein the recording layer is initialized with light having a wavelength &lgr; incident from the second dielectric layer side, and the thickness of the second dielectric layer is in a range of &lgr;/(12×n) to &lgr;/(2×n) (where n is a refractive index of the second dielectric layer).