The purpose of this study was to investigate the effect of the aqueous extract of the Astragalus membranaceous(AM). AM showed inhibitory effect on the tyrosinase activity using L-tyrosine as a substrate. Tyrosinase plays an important role in the process of melanin polymer biosynthesis. In vitro AM extract(1mg/ml) inhibited melanin biosynthesis and are useful for the material used in cosmetics. B16 mouse melanoma cells were cultured in different concentrations. The non-cytotoxicity of the plant extracts was confirmed by MTT assay.