Omija berry (Schisandra fructus) is a traditional Korean fruit, which contains lots of medicinal ingredients. In order to analyze whether Omija contains antibacterial components, we extracted Omija using five different methods including water precipitation, ethanol precipitation, hot water extract, methanol-ultrasonication, and water-ultrasonication, and examined their antimicrobial activities against Escherichia coli (E. coli), and Bacillus cereus (B. cereus). Most of Omija extracts did not inhibit bacteria growth in the paper disc diffusion assay except hot water extract for 60 minutes. Hot water extract for 60 minutes made clear inhibition zone around the disc at all the concentrations (x1, x1/10, x1/100) in both E. coli and B. cereus. However, hot water extracts for 90 minutes and 120 minutes showed antimicrobial activities only at x1 stock solution, which indicates that 60 minutes extraction at hot water is the best method to obtain Omija extract with the best antimicrobial activities in disc diffusion assay. In turbidimetric assay, water extract in soak, hot water extract, and methanol extract in ultrasonicator inhibited growth of both E. coli and B. cereus. Ethanol extract in soak and water extract in ultrasonicator had no effect on bacterial growth in both E. coli and B. cereus. In this study, we found that Omija extracts showed antimicrobial activities against E. coli and B. cereus. Therefore, water soluble materials of Omija can be used as a drink supplement and developed as an antibacterial cleanser.