The possibilities of utilizing acid-hydrolyzate of "Sliced and dried sweet potatoes" as a carbon source for the microbial production of L-Glutamic Acid(L-GA) with Micrococcus glutamicus were investigated and the results showed as follows： 1) The highest hydrolysis rate, 74.6% of the reducing sugar based on the weight of dry matter, was obtained when the sweet potatoes were hydrolyzed with 0.8% of HCI at 2.0kg/$cm^2$ for 30 minutes. The most favorable hydrolyzate for the growth of the cells, however, was found to be the one obtained by treating the sweet potatoes with 0.5% HCI at 2. 0kg/$cm^2$ for 10 minutes. Reducing sugar content of the hydrolyzate was 10% as glucose. 2) Biotin content of the hydrolyzate was 25$mug$/1 and it was proved to be excess in amount for the L-GA production. 3) The effects of addition of antibiotics, alcohols and fatty acid esters on the L-GA production were tested in the biotin excess medium. The production of L-GA was most increased to 32.5g/l with the addition of 10 I. U. of penicillin per ml. to the culture medium at 4 hours after inoculation. But the addition of alcohols, especially fatty acid esters, showed no significant effects. 4) Among the organic nutrients tested. " Gluten acid hydrolyzate" greatly enhanced the production of L-GA adding it＇s concentration of 1.0% to the medium. 5) The maximum production of L-GA resulted in 35g/1 when the cells were grown for 48 hours in the hydrolyzate medium supplemented with 1.0% of "Gluten acid hydrolyfate" and with 10 I. U. of penicillin per ml added at 4 hours after cultivation.