Effects of methanolic extract from Adenophorae Radix (AR) on melanogenesis were investigated in mouse melanoma B16F10 cells. The methanol extract of AR was partitioned into Hexane, Ethyl acetate (EA), Butanol, H₂O, and exogenously added to the culture medium for 72 hours at the concentration of 10, 50, 100 and 200 ㎍/㎖. Of the four partitions, Hexane and EA partion of AR reduced tyrosinase activity, which is the key enzyme for a melanogenesis, as well as melanin contents. But the EA partition was less toxic for B16F10 cells and has more efficient melanin-reducing effect than the former. In addition, the EA partition dramatically lightened the color of cell pellet and significantly decreased the level of tyrosinase protein expression. In these results, EA partition of AR reduced melanin synthesis of B16F10 mouse melanoma cells by down regulating the tyrosinase activity and tyrosinase protein expression. Therefore, it is anticipated that AR is a candidate for an efficient whitening agent which supresses melanogenesis.