The present invention provides an optical information recording medium of
excellent signal quality in high density recording onto a semitransparent
information layer, its manufacturing method and a manufacturing
apparatus. The optical information recording medium of the present
invention includes at least a semitransparent information layer disposed
between a circular transparent substrate and a protective substrate, in
which the information layer has spiral grooves for guiding a light beam,
and also includes a recording film capable of recording/reproducing
information thereon/therefrom by changing at least in two states
detectable optically by irradiation of the light beam from the
transparent substrate side, and the difference in film thickness of slope
portions of the inner circumferential side and outer circumferential side
of the groove is within .+-.10% in the entire region for
recording/reproducing information.