It was researched the maximum activity conditions of microorganism and agarase which has high degrading activity for the production of agaro-oligosaccharide. From this experiment, the optimum conditions for reduced sugar production of Bacillus cereus ASK202 were observed to be temperature 25℃, initial pH 7.0, respectively. Maximum cell growth and agar degrading activity was observed after 27 hours of cultivation. The higher concentration of enzyme, the higher degrading activity. The maximum conditions of reduced sugar production for agarase were temperature 40℃, pH 7.0 and agar concentration 0.4%(w/v), respectively.