Chestnut bark extract by methanol repressed the expression of tyrosinase gene of B16 mouse melanoma cell containing tyrosinase promoter. $10{mu}g/ml{ell};100{mu}g/m{ell}$, $1mg/m{ell}$ of the extract repressed expression of tyrosinase gene about $38\%,;47\%,;and;78\%$, respectively, compared with control. In the MTT assay, the same extract exhibited very low cytotoxicity at $1{mu}g/m{ell},;10{mu}g/m{ell},;100{mu}g/m{ell},;and;1mg/m{ell}$, respectively. The fractions of Methylene chloride and ethyl acetate did not showed the repressive effect on the expression of tyrosinase gene, but the fraction of butyl alcohol repressed highly at $10{mu}g/m{ell};and;100{mu}g/m{ell}$.