The inulinase producing microorganism was isolated from soil and tentatively identified as Arthrobacter protophormiae/ramosus. Inulinase was pruified by ethanol precipitation, DEAE-Sephadex ion exchange chromatography and Sephadex gel filtration chromatography. The molecular weight of the purified enzyme was 34 kDa. The specific activity, yield and purity were 31.5 Unit/mg, 19.5% and 18.5 fold, respectively. Optimal pH and temperature for reaction of the purified inulinase were 8.5 and $55^{circ}C$, respectively. The enzyme was stable at pH 7.5, below$ 55^{circ}C$, and the activity was stimulated Mg2+.