PURPOSE: To inexpensively purify a cyclic inulooligosaccharide capable of expecting utilization in chemical field and other wide fields in high yield without using any solvent from a solution containing the cyclic inulooligosaeeharide.

CONSTITUTION: A sugar solution containing a cyclic inulooligosaccharide binding fructose molecules in a cyclic state by β-(2-1) bond, a monosaccharide, a disaccharide, a straight-chain oligosaccharide and inulin is reacted with an exo type enzyme having ability to cleave β-(2→1) fructoside bond or a microorganism producing the enzyme and the cyclic inulooligosaccharide is collected from the resultant sugar solution to purify the objective cyclic inulooligosaccharide.