The antioxidant activity of Bacillus polyfermenticus SCD was studied by partially purified culture extracts using various methods: ammonium sulfate precipitation, adsorption to Diaion HP-20 columns using polar solvents, and extraction using non-polar solvents. The 1,1-diphenyl-2-picyrylhydrazyl (DPPH) radical scavenging activity of these partially purified fractions was then investigated. The precipitate isolated using 75%-saturated ammonium sulfate was shown to contain about 77.2% DPPH radical scavenging activity. Using the Diaion HP-20 resin adsorption method, the fraction obtained using 60% ethanol and 60% methanol possessed 76.7 and 89.5% DPPH radical scavenging activity, respectively. Fractions obtained by extracting with the non-polar solvents 80 mg/mL chloroform, 80 mg/mL n-hexane, 80 mg/mL ethyl acetate, and 80 mg/mL butanol contained 68.4, 75.0, 70.7, and 87.5% DPPH radical scavenging activity, respectively. Further study is needed to characterize the antioxidant substance(s) released by B. polyfermenticus SCD cultures.