Multilayer phase-change information recording medium, and method for recording and reproducing using the same

The object of the present invention is to provide a multilayer phase-change information recording medium comprises a substrate, and N layers of information layer (N represents an integral number of 2 or more), and each of the information layers comprises at least a recording layer in which information is recorded by irradiating laser beam to induce a phase change between crystalline phase and amorphous phase. The present invention is characterized in that when the information layer is disposed so that a first information layer, a second information layer, a third information layer . . . , and N information layer are disposed in this sequence from the laser beam irradiation side, at least one information layer other than the N information layer comprises a lower protective layer, a recording layer, an upper protective layer, a reflective layer, and a thermal diffusion layer disposed in this sequence from the laser beam irradiation side; the thermal diffusion layer comprises at least indium (In) and oxygen (O) and further comprises any one of titanium (Ti) and zirconia (Zr); and the atomic ratio of indium (In) to all the metal elements in the thermal diffusion layer, In/all the metal elements, is 0.75 to 0.9.