In order to study on the viscous substance produced during Chungkookjang fermentation, one strain which produce a lot of viscous substance was isolated from the rice straw and identified as Bacillus sp. This strain produced the most viscous substance in 48 hours at 42℃, in splite of little change of amino type nitrogen and ammonia type nitrogen when added M.S.G., while the yield of viscous, substance and amino type nitrogen was increased but that of ammonia type nitrogen was decreased when added susrose. Molecular weight of viscous substance estimated between 15,000 and 65,000. Viscous substance was confirmed mostly composed of glutamate and fructose by G.C. and HPLC analysis. Composition of viscous substance would be controlled according to the changes of media.