Optical information recording medium

An optical information recording medium for recording and reproducing information by irradiation with a laser beam having a wavelength λ of 450 nm or less, comprising:

• a substrate;
• and
• a plurality of information layers formed on the substrate,
• wherein a first information layer closest to an incident side of the laser beam among the plurality of information layers includes a recording layer, a reflection layer and a transmittance adjusting layer in this order from the incident side,
• the recording layer is reversibly changed between a crystal phase and an amorphous phase by irradiation with the laser beam,
• assuming that a transmittance of the first information layer at the wavelength λ in a case of the recording layer in a crystal phase is Tc1 (%) and a transmittance of the first information layer at the wavelength λ in a case of the recording layer in an amorphous phase is Ta1 (%), the Tc1 and Ta1 satisfy 46<Tc1 and 46<Ta1, and
• assuming that a refractive index and an extinction coefficient of the transmittance adjusting layer at the wavelength λ are n1 and k1, respectively, and a refractive index and an extinction coefficient of the reflection layer at the wavelength λ are n2 and k2, respectively, the n1, the k1, the n2 and the k2 satisfy 1.5≦(n1−n2) and 1.5≦(k2−k1).