To develop an whitening cosmetics, we isolated the melanogenesis inhibitors from the unripe fruits of Poncirus trifoliata (Rutaceae). Isolated compounds were identified as poncirin(l), naringin(2), bis(2-methylheptyl)phthalate(3), avenalumic acid methyl ester(4) by comparison of physical and spectral data with those reported in the literature. Among the isolated compounds, bis(2-methylheptyl)phthalate showed most potent inhibitory effect on the melanogenesis in cultured B-16 mouse melanoma cell lines$(IC_{50},;36.8;{mu}M)$ compared with kojic acid$(IC_{50},;150;{mu}M)$.