PURPOSE: To increase the S-N ratio of a reproduced information signal.

CONSTITUTION: This optical disk consists of a discoid substrate 1 having 83-95% laser light transmissivity made of a transparent material contg. a light absorbing substance having absorption to laser light, an information recording layer 2 formed on one side 1a of the substrate 1 and a protective layer 3 formed on the surface of the recording layer 2. Carbon black may be used as the light absorbing substance and laser light scattering in the substrate 1 and returning to an optical pickup as noise is absorbed in the light absorbing substance. The protective layer 3 is preferably formed as a light absorbing layer having absorption to laser light. This light absorbing layer may be formed on the entire surface of the substrate 1 except the readout region.