The MeOH extract of the bark of Paeonia moutan showed potent inhibitory effect on the mushroom tyrosinase activity in vitro. The activity-guided fractionation of t he MeOH extract resulted in the isolation of three active compounds. The chemical structures of these compounds were elucidated by chemical and spectroscopic evidence as catechin, 1,2,3,6-tetra-O-galloyl-${eta}$-D-glucose and 1,2,3,4,6-penta-0-galloyl-${eta}$-D-glucose, respectively. Among them, the inhibitory activity by 1,2,3,6-tetra-galloyl-${eta}$-D-glucose on mushroom tyrosinase was more potent $(IC_{50}=3.5;{mu}M)$ than that of kojic acid $(IC_{50}=8.7;{mu}M)$ ,but catechin enhanced the mushroom tyrosinase activity 50% in the concentration of 34.5M.