This study aimed to evaluate the antioxidative efficacies of Stephanandra incisa methanolic and ethanolic extracts (SIME and SIEE, respectively) in a cell-free system. Respective total polyphenol contents of SIME and SIEE were 12.8 and 17.9 tannic acid equivalents (TAE) mg/g, and respective total flavonoid contents were 0.38 and 0.39 quercetin equivalents (QE) mg/g. At 1,000 μg/mL, respective ABTS+ radical scavenging activities of SIME and SIEE were 97.4% and 99.1%, respective ferric reducing antioxidant powers were 28.1 and 37.9 μM/g, and respective hydrogen peroxide scavenging activities were 28.4% and 32.8%. These results suggest that SIEE possesses higher antioxidative efficacy than SIME.