A first recording film, interlayer, and second recording film are formed
on a transparent resin substrate having a groove and land. A recording
mark is formed by irradiation with a short-wavelength laser beam. The
light reflectance of the recording mark formed by irradiation with the
short-wavelength laser beam is higher than a light reflectance before
irradiation with the short-wavelength laser beam. The groove wobbles
within a predetermined amplitude range. A resin material forming the
interlayer is a polymer material containing carbon, hydrogen, nitrogen,
and oxygen as main components. The oxygen atomic ratio is 11 atm % or
more, or the push-pull signal modulation degree is 0.26 or more.