To estimate the inhibitory effect of Rubus coreanum extract on melanin biosynthesis, we tested its inhibitory effects on tyrosinase promoter in B16 mouse melanoma cells. Rubus coreanum extract by methanol had inhibitory effect approximately 10% on tyrosinase promoter at $100{mu}g/mL$. In the MTT assay, the same extract exhibited very low cytotoxicity under $100{mu}g/mL$. The fractions of methylene chloride, butyl alcohol and water did not showed the inhibitory effect on tyrosinase promoter, but the fraction of ethyl acetate exhibited inhibitory effect approximately 11% at $100{mu}g/mL$.