This study was conducted to investigate the tyrosinase inhibitory and melanin production inhibitory activity of the distilled water extract of Dendropanax morbifera leaf (DMW) and the fermented extract by Lactobacillus plantarum (DMF). DMF was prepared by inoculation of L. plantarum after the extraction procedure with distilled water. Fermentation for 48 hours at 37℃ is the most effective condition in this study. In DPPH radical scavenging ability, SC50 values of the fermented DMF was 37.9 μg/ml as a result of more effective than DMW extract (52.6 μg/ml). Moreover, tyrosinase inhibitory activity of DMF showed higher activity than DMW. In nontoxic concentration range, DMF showed strong melanin production inhibitory effect in α-melanocyte stimulating hormone-stimulated B16F10 cell. As a result, the fermentation of the distilled water extract of D. morbifera leaf by L. plantarum could be applicable to functional materials production for skin-whitening agents.