The purpose of this study was to investigate the mechanism of ethanol extract of Agrimonia pilosa Ledeb. (EAP)-reduced melanogenesis and diphenyl-picryl-hydrazyl (DPPH) radical scavenging activity. Agrimonia pilosa Ledeb., a perennial herbaceous plant, has been used as an antihemorrhagic, anthelminntic, and antiinflammatory agents in Chinese herbal medicine. In the present study, we observed that melanin synthesis and tyrosinase activity of B16F10 cells were significantly decreased by EAP. However, EAP could not suppress tyrosinase activity in the cell-free system, whereas kojic acid directly inhibited tyrosinase activity. Furthermore, EAP decreased the protein expression of tyrosinase, tyrosinase-related prootein 1 (TRP-1), and tyrosinase-related prootein 2 (TRP-2). EAP scavenged DPPH radical up to 41% with 100 ${mu}g/m{ell}$ concentration. These results suggest that the hypopigmentary effect of EPA was due to regulation of tyrosinase protein.