An antioxidant activity of Gardenia Fruit (Gardenia jasminoides Ellis) which has been used for food coloring was studied. The antioxidant activity was determined by measuring lipid peroxide produced when a mouse liver homogenate was exposed to the air at $37^{circ}C$, using 2-thiobarbituric acid (TBA). Both water and methanol extracts of Gardenia Fruit showed the antioxidant activity. On solvent fractionation, the antioxidant activity was removed into the ethyl acetate and butanol soluble fractions. And the final water soluble fraction also showed the antioxidant activity in the low concentration, but it promoted the lipid peroxidation in the high concentration. Two compounds (I and II) having the antioxidant activity were isolated from the butanol fraction, and compound I also occurred in the ethyl acetate fraction. The antioxidant activity of compound II was more potent than that of I. By analyzing data for UV, IR and $^1H-NMR$, compounds I and II were identified as geniposide and crocin, respectively.