1. An information recording medium, comprising a recording layer whose phase changes by irradiation with a laser beam or application of current, wherein the recording layer contains, as its main component, a composite composed of Ge, Sb, and Te, and the composite has a composition within a region enclosed by: point (e) (25, 75, 0), point (f) (25, 65, 10), point (g) (7.2, 65, 27.8), and point (h) (10, 90, 0) in terms of a coordinate (Ge, Sb, Te)=(x, y, z) on a triangular coordinate shown in FIG. 1 , wherein point (g) corresponds to a point at Sb=65 on Te—Ge 10 Sb 90 , and the region includes lines extending between point (e) and point (f), point (f) and point (g), and point (g) and point (h), and the region excludes a line extending between point (h) and point (e).