The tyrosinase inhibition activity and mutagenicity as assessed by the Ames test on phenolic antioxidants (5-Caffeoyl quinic acid, 3,4-Dihydroxy cinnamic acid, Quercetin 3-O-${eta}$-D-glucopyranose, Kaempferol 3-O-${eta}$- D-glucopyranose) and the ethyl acetate fraction isolated from mulberry leaves were examined. The ethyl acetate fraction and chlorogenic acid exhibited weaker tyrosinase inhibitory activities than kojic acid. In addition, the ethyl acetate fraction from mulberry leaves, containing phenolic antioxidants, showed no mutagenicity by the Ames test.