Cycloinulooligosaccharide fructanotransferase (CFTase) converts inulin into cycloinulooligosaccharides (cyclofructan, CF) of ${eta}-(2{ o}1)$-linked D-fructofuranose as well as hydrolysis of cyclofructan. Sequences analysis indicated that CFTase was divided into five distinct regions containing three repeated sequences (R1, R3, and R4) at the N-terminus and C-terminus. Each domain function was investigated by comparison of wild type CFTase enzyme (CFT148) and deletion mutant proteins (CFT108: R1 and R3 deletion; CFT130: R4 deletion; and CFT88: R1, R3, and R4 deletion) of CFTase. The CFT108 mutant had both CFTase and CF hydrolyzing activity as CFT148 did. CFTase activities and CF hydrolysing activities were disappeared in CFT130 and CFT88 mutants. These results indicated that the C-terminal R4 region of P. polymyxa CFTase is necessary for cyclization and hydrolyzing activity.