Inulo-oligosaccharides were produced from inulin by using high activities of an endo-acting inulinase. The total yields of oligosaccharide were slightly decreased as the concentration of inulin increased from 50 to 200 g/l. Under the optimal reaction conditions, the products consist of inulo-oligosaccharides ranging from DP (degrees of polymerization)2 to DP7, where the major oligosaccharides are 29.8% DP2, 21.4% DP3, and 8.1% DP4 oligomer, respectively. The maximum yield was 75.6% when 50 g inulin/l and 15 units/g substrate were used.