Whitening effect, which decreases the skin pigmentation, is the one of important targets in cosmetics. This study was investigated the effects of Scirpi rhizoma on ant ioxidation and melanogenesis. S.rhizoma is a rhizome of Scirpus fluviatilis G. a perennial Cyperaceae species of wide occurrence in Asia, Europe, Africa and North America. S.rhizoma shown scavenging activities of free radicals and reactive oxygen species (ROS) with the IC50 of 638${mu}g/ml$ against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and 21.7${mu}g/ml$ against superoxide radicals in the xanthine/xanthine oxidase system, respectively. S.rhizoma treatment (48 h) suppressed the biosynthesis of melanin up to 27% and reduced tyrosinase activity up to 31% at 100${mu}g/ml$ in B16 melanoma cells. S.rhizoma was also able to significantly inhibit tyrosinase and TRP-1 expres- sion in protein level. These results suggest that S.rhizoma inhibited melanin biosynthesis by regulating tyrosinase activity and expression in B16 melanoma cells. Therefore S.rhizoma may be useful as new whitening agent due to the antioxidant effect and the inhibitory effect against melanogenesis.