By treating crude enzyme extract from Aspergillus kawachii, the liquiritigenin content in the licorice (Glycyrrhizae Radix) was significantly increased. The liquiritigenin content reached its maximum level (45.7 mg/g licorice extract) after 60 min of incubation with the crude enzyme extract at $37^{circ}C$, while the inactivated crude enzyme treated control contained trace amount (about 0.11 mg/g) of liquiritigenin. The enzyme-treated licorice extract inhibited more than 50% DPPH radical at 100 ppm and this was about two times higher activity compared to the enzyme-untreated control.