PURPOSE: To produce an amino acid from cellulosic material, by culturing an amino acid-producing strain in a fermentation system containing a cellulosic material as a main component in the presence of cellulase and cellobiase.

CONSTITUTION: A medium composed of 1W30% cellulosic material (e.g. wood, rice straw, bagasse, chaff, etc.) and nitrogen source, inorganic source and other nutrient sources necessary in the amino acid fermentation, is mixed with cellulase, cellobiase and precultured bacterial strain capable of producing amino acid, and is fermented at 4W6pH and 25W40°C for 1W7 days to obtain amino acid. The amounts of cellulase and cellobiase are 1W30wt% and 1W10wt% based on the cellulosic material, respectively.