Cyclodextrinase from B. stearothemophilus KJ16 that can produce both cyclodextrin(CD) glucanotransferase and cyclodextrinase was purified 87.6-fold with 7% yield by ammonium sulfate precipitation, DEAE-cellulose chromatog-raphy, Sephadex G-100 chromatography, and FPLC. The molecular weight of the purified enzyme was about 68,000 dalton by SDS-PAGE. The optimal pH and temperature were 6.0 and 55$^{circ}C$, respectively. The enzyme was stable at 5$0^{circ}C$ for 2 hr in the pH range of 5.5 and 8.5. The enzyme activity was inhibited strongly by mercaptoethanol, di-thiothreitol, p-chloromercuribenzoate, N-bromosuccinimide, $Cu^{+2}$and $Hg^{+2}$. The purified enzyme hydrolyzed CDs with$gamma$-CD>$eta$-CD>$alpha$-CD. The enzyme also hydrolyzed linear maltodextrins and polysaccharides, but the rates of hyd-rolysis for such substrates were slow as compared to that for $gamma$-CD. The final degradation products with all substrates were maltose and glucose. Maltose was not further hydrolyzed.