To provide a recording medium allowing the recording, reproducing and overwriting at either optical wavelengths of 635 nm and 420 nm in a phase transition optical information recording medium.

This phase transition optical information recording medium has a multilayer structure comprising at least one recording layer, dielectric layer and reflective layer respectively on a transparent substrate and, further, is constituted in such a manner that the erasing level (crystal level) at on optical wavelength of 420 nm is ≥70% of the erasing level at an optical wavelength 635 nm and the reflectance at the optical wavelength 420 nm is ≥10%.