A strain of Trichoderm sp. J-30 which strongly products cellulase to reduce the content of cellulose in the stem of leaf tobacco was isolated from leaf tobaco. The Trichoderma sp. J-30 was identified as Trochoderma voride. The cellulase from this strain was purified with the physico-chemical methods and treated in the culled stem of leaf tobacco. The results obtained were summarized as follows. 1. Optimal pH of the enzyme was at pH 5.0. 2. The enzyme shooed a higher activity at $40^{circ}C$ and its thermal stability began to decrease at $60^{circ}C$. 3. The enzyme activity was promoted by the metal ions such as $Ca^{2+}, Mg^{2+}, Pb^{2+}and;Zn^{2+}.$ 4. When the culled stem of leaf tobacco was applied with the 3% of the enzyme solution at $40^{circ}C$ for 3 days. 15 to 17% of cellulose contents decreased, 12 to 13% of total sugar increased and the filling power was increased by 10-13% in the sample.