PURPOSE: To perform recording having a high S/N, reduced in a bit error rate and enhanced in thermal stability by providing a recording layer wherein at least two kinds of phases mutually forming no solid solution are mixed and dispersed on a substrate.

CONSTITUTION: As a recording layer, one wherein two kinds of minute particle phases l, 2 mutually forming no solid solution are mixed and dispersed or one wherein the minute particle phase 1 is mixed with and dispersed in a matrix phase 3 forming no solid solution along with the phase 1 is designated. One of the phase components constituting the recording layer is selected from Au, Ag, Rh, Pd, Pt, Ru, Ir, Os, Re, Al, Cu, Ni, Co and Cr and the other component is selected from Cd, Hg, Ca, In, Tl, Sn, Pb, As, Sb and Bi. In the recording layer, the m.p. of at least one phase is desirably 500°C or lower and, when the m.p. of all of the phases is 500°C or higher, the phase separation due to the irradiation with heat source light becomes insufficient and there is possibility such that no high S/N ratio is obtained.