A disc-shaped recording medium having transcription characteristics for fine
signals
simultaneously with resonance characteristics and stiffness which are characteristics
contrary to the transcription characteristics. At least a recording layer and a
light transmitting layer are sequentially formed on a substrate and light is illuminated
from a light transmitting layer side to record and/or reproduce information signals.
The substrate includes a core layer formed of a resin composition comprised of
a mixture of two or more resin sorts. The resin composition has tan, as
an index indicating the internal loss, equal to not less than 0.015 as a system
in its entirety. The resin composition constituting the core layer is a compounded
resin of the incompatible system and is of an islands-sea structure.
