CGTase enzymatically acts on starch, dextrin, amylopectin, and amylose to produce primarily γ-CD, with quantities of β- and α-CD produced being smaller than the quantity of γ-CD produced, has an optimum pH of 10.5-11.0, an optimum temperature of about 60° C., a stable pH of 6-11, and temperature stability, exhibits residual activity of not less than 90 percent with a 15 minute-treatment at 50° C., is produced by culturing a Bacillus clarkii (for example, FERM B-7156), reacts with starch or the like to produce principally γ-cyclodextrin.