With the disc-shaped recording medium, or the disc manufacturing method
according to the present invention, for both the single-layer disc and
the multi-layer disc, a recording layer L0, which is to be the first
layer, is at the same distance, along the direction of disc thickness,
from the surface of the cover layer CVLs on which falls the laser light.
For the multi-layer disc, the second layer L1 and the following layer(s)
are formed at the locations which are closer to the cover layer CVLs than
the first layer L0. Management information may be recorded by mobbling
grooves, each layermay have tert areas, defect information, a replacement
area. Thus, it is possible to improve compatibility, reliability and
accessibility between a single-layer disc and a multi-layer disc. The
spherical aberration for the recording/reproducing light may be
controlled with respect to the selected layer.