Cinnamomi Cortex (Lauraceae), the dried bark of Cinnamomum cassia BLUME, has been used as traditional Chinese medicine for its stomachic, astringent, carminative, antispasmodic, antibacterial, antifungal properties. Four compounds were isolated from the MeOH extract of Cinnamomi Cortex, and their structures were identified as trans-cinnamic acid (1), ${eta}-sitosterol$ (2), bis(2-methylheptyl)phthalate (3), coumarin (4) by comparison of their physical and spectral data with those reported in the literature. These compounds were tested melanogenesis inhibitory effect on B-16 mouse melanoma cell lines. Among them, trans-cinnamic acid (1) showed the most potent inhibitory effect on melanogenesis with $IC_{50}$ value of $13{mu}g/ml$. Arbutin, positive control, exhibited an $IC_{50}$ value of $29{mu}g/ml$.