Eggplant extract markedly inhibited melanogenesis in B16 mouse melanoma 4A5 cells (B16 cells). To clarify the characteristics of the melanogenesis inhibitor in eggplant, the effective fraction, P1, was separated from the eggplant extract by ammonium sulfate fractionation and Sephadex G-100 column chromatography. The P1 fraction from the eggplant contained 63% protein, 20% neutral sugar and 11% uronic acid. P1 was stable during heating at 60°C for 30 min, and the inhibitory effect remained stable after protease digestion. P1 weakly inhibited tyrosinase activity in crude B16 cell extract in vitro, and tyrosinase activity in B16 cells cultured with P1 was reduced. The regulation of tyrosinase activity in B16 cells was equal to melanogenesis suppression in B16 cells. These results show that the eggplant extract suppresses melanogenesis in B16 cells by regulation of tyrosinase.