Total 29 Monascus strains were isolated from Ang-Khak and 4 of them were selects based on the relative intensity of soluble red pigment and growth rate. The optimum growth temperature of all the selected isolates was 32.5℃ on malt extract agar(MEA) plate. The optimum growth pH was 5.0 on czapek yeast extract agar plate, while it was pH 6.2 or 6.5 on MEA plate. Isolate No. 116, especially, showed the strongest antimicrobial activity aganist Bacillus subtilis and Staphylococcus aureus but much less aganist Escherichia coli and Enterobacter aerogenes. The maximun antimicrobial activity of isolate No. 116 against St. aureus was achieved at initial pH 5.3 on rice extract broth. The acitivity was increased with increasing amount of culture broth concentrate of isolate No. 116.