Recent studies have revealed pleiotropic anticancer and antiproliferative capabilities of Dioscorea nipponica Makino whereas the effect of this plant on metastasis of cancer cells has not been clearly clarified. In the present study, we extracted Dioscorea nipponica Makino with methanol (DNE1), chloroform (DNE2), ethyl acetate (DNE3), n-butanol (DNE4), and water (DNE5). We first demonstrate that DNE3 was found to be effective in reducing the lung metastases formation by about 99.5% as compared to vehicle-treated control animals. When a nontoxic concentration of the extract was treated directly to highly metastatic murin melanoma cells (B16F10) and human melanoma cells (A2058) in vitro, it exerted a dose-dependent inhibitory effect on the invasion (P < .001), motility (P < .001), secretion of MMPs (P < .001), and u-PA (P < .001) of both cell lines. To investigate the possible mechanisms involved in these events, we performed western blot analysis to find that DNE inhibited phosphorylation of Akt. A treatment with DNE3 to B16F10 cells also inhibited the activation of NF-κB and increased the expression of IkappaB. Taken together, these findings suggested that DNE3 could reduce the metastasis of melanoma cells, thereby constituting an adjuvant treatment for metastasis control.