A magneto-optical recording medium having a recording layer made of a bismuth-substituted garnet and deposited by a sputtering over an amorphous substrate of aluminosilicate or borosilicate glass, the recording medium including a garnet underlayer of either a double-layer or single-layer structure. The formation of an underlayer of a double-layer structure made of garnet reduces the level of noise due to light scattering at crystalline boundaries in the garnet film. The formation of an underlayer of a single-layer structure made of a garnet having a lower crystallization temperature than a YIG film is also effective to noise-level reduction. An underlayer has a surface smoothness corresponding to a roughness of approximately 10 .ANG., which is improved from the surface smoothness of a conventional underlayer comprising a YIG film.