To provide a hydrogen-embrittlement-proof and highly corrosion-resistant surface treatment on the surface of an R-T-B based rare earth magnet (R stands for at least one rare earth element containing Y, and T stands for Fe, or Fe and Co).

The surface treatment includes: forming an aluminum coating with an aluminum electroplating solution using non-aqueous solvent on the surface of an R-T-B-based rare earth magnet (R stands for at least one rare earth element containing Y, and T stands for Fe, or Fe and Co); and further changing part of the aluminum coating into an oxide film through thermal hydroxidation or anodization; thereby forming a hydrogen-embrittlement-proof and highly corrosion-resistant coating.