In order to increase the rate of kojic production using Aspergillus oryzae, the initial glucose and Polypepton concentrations were optimized by the Box-Wilson method. A kojic acid production rate of 4.44 g/l . d was obtained when the initial glucose and Polypepton concentrations were 148.0 g/l and 4.8 g/l, respectively, at a K(L)a value of 164.7 h(-1).