At least one information layer including a recording layer contains a material
that can exhibit a transition between two optically different states in response
to irradiation with a laser beam as a main component is provided on a substrate,
and the material is configured so as to exhibit an energy gap ranging from 0.9
eV to 2.0 eV in the amorphous state. The information layer is configured to have
a light transmittance of not less than 30% when irradiated with a laser beam having
a wavelength ranging from 300 nm to 450 nm. It is possible to achieve excellent
recording/reproduction, even if a plurality of recording layers are provided in
the recording medium, when this medium is irradiated with a laser beam with a wavelength
in the foregoing range from one side of the medium.