A 3.0-kb DNA fragment containing an endo-inulinase gene was cloned from Arthrobacter sp. S37. It contained a single open reading frame of 2439 bp, encoding a polypeptide composed of signal peptide of 53 amino acids and mature protein of 759 amino acids. From the comparison with amino acids sequences of fructan hydrolases and invertase, five highly conserved regions including the beta-fructosidase motif were found. The sequence of the endo-inulinase had the identity in the range of 13.3% to 16.0%.