Hardness of a resin substrate of an optical disc is selected to be greater
than hardness of a cover layer of the optical disc, at least when
information is recorded on the optical disc. A laser beam is transmitted
to an organic dye layer of the optical disc through the cover layer and a
protection layer when information is recorded on the optical disc. The
organic dye layer is sandwiched by the protection layer and a reflection
layer. The substrate has grooves on its surface, and information is
recorded between the grooves. The organic dye is heated and expands upon
information recording, but a stress generated by the deforming organic
dye layer is mainly transferred toward the cover layer. Deformation of
the reflection layer and crosswrite upon information recording can be
prevented. Therefore, the optical disc can record information between the
grooves at a high density. Alternatively, the optical disc may be
configured such that heat transfer toward the protection layer from the
organic dye layer is set to be greater than heat transfer toward the
reflection layer from the organic dye layer when the light beam is
radiated for information recording.