To identify antimicrobial activities of soybean paste, studies have been carried out with laboratory manufactured soybean paste, traditional and improved type soybean paste purchased on the market. The soybean paste fermented with Aspergillus oryzae and Rhizopus tamari and commercial soybean paste were shown antimicrobial activities for Bacillus cereus, Escherichia coli, Listeria monocytogenes, Staphy lococcus aureus, Streptococcus faecalis, Escherichia coli O157:H7, Bacillus subtilis and Salmonella typhimurium. Non fermented soybean paste did not show antimicrobial activities against Bacillus cereus, Escherichia coli, Listeria monocytogenes, Staphylococcus aureus and Streptococcus faecalis. The extract of soybean paste extracted by 80% methanol showed the highest antimicrobial activities of in ethyl acetate fraction and followed butanol fraction, respectively. Antimicrobial activities of traditional and improved type soybean paste were shown against all tested microorganisms and clear zone length of traditional soybean paste was slightly larger than that of improved type. Components of antimicrobial fractions of soybean paste were guessed peptides, 4 hydroxy benzoic acid, benzoic acid by GC MS.