Chitinase and chitobiase produced by Aeromonas sp. J-5003 were purified and characterized. The chitinase was purified to 19.4 folds by gel chromatography and ion-exchange chromatography with the overall yield of $2.2\%$ and the specific activity of 93.1 unit/mg. The purified enzyme showed a single band on SDS-PAGE with MW 54kDa. The optimum pH and temperature of the purified chitinase were 7.0 and $37^{circ}C$, respectively, and this enzyme stable in the range of pH 6.0 to 10.0 below $37^{circ}C$. $Mg^{2+},;Ca^{2+};and;Na^+$ slightly stimulated the chitinase activity. However, $Hg^{2+};and;Fe^{3+}$ inhibited chitinase activity. The chitobiase was purified by Sephacryl HR-l00 gel chromatography and DEAE-Sephadex A-50 ion-exchange chromatography with 33.5 purification folds and $4.3\%$ yield. The purified enzyme showed a single band with MW 63 kDa. The optimum pH and temperature of the purified chitobiase were 7.0 and $37^{circ}C$, respectively. And this enzyme was stable in the range of pH 6.0 to 9.0 and at the temperature below $37^{circ}C$. The enzyme activity was increased by $Mn^{2+}$, but it was inhibited by $Ag^+$.