We investigated the quality of soybean paste(Doenjang) fermented by BAcillus brevis. The results obtained were as follows : soybean paste fermented by Bacillus brevis had alkaline pH and yellow ochre color. Dextrinizing activity was about 98 D.P. unit from 5th to 25th day of fermentation at 3$0^{circ}C$ and after that day somewhat decreased . Saccharifying activity was respectively 6.1, 7.2, 6.8, 6.4 S.P. unit on 5, 15, 25 and 35th day of fermentation. Protease activity suddenly increased after 15th day of fermentation and was 250, 275, 299 unit on15, 25, 35 th day of fermentation , respectively. The most abundant free amino acid was found to be glutamic acid (561.8mg%) in soybean paste fermented by Bacillus brevis. In case of free sugar and non-volatile organic acid, fructose and oxalic acid showed highest content of 10.25mg% on 25th day and 12.20mg% on 15th day. The contents of free amino acids, free sugars, organic acids in soybean paste fermented by B.brevis were most abundant after 25 days of fermentation and this results were similar to that of traditional soybean paste. The odor of soybean paste fermented by Bacillus brevis was improved to be a nice soybean paste odor on 25th day of fermentation. However, sensory evaluation value of the taste of it decreased after 10 th day of fermentation.