Studies on some properties of cellulase isolated from Piricularia oryzae. Crude cellulases were prepared from dried rice plant powder (Tong-il, Pal-dal) culture of P. oryzae(N-2, C-8, T-2). The best yield of enzyme was obtained from the medium using Tong-il rice plant powder for P. oryzae cav. N-2 and 2%-sucrose concentration in preculture media. Two units of the enzyme were incubated at $60^{circ}C$ for 1 hour with 1.0ml, 0.6% Na-CMC. The optimum temperature for the enzyme activity was at $60^{circ}C$ and the optimum pH was at pH4.0. When Na-CMC was used as substrate the $K_m$ values of crude enzyme were calculated to be $1.05{ imes}10^{-4};mM;and;V_{max}$ was 2.8 mmole/hour. A 10-fold partial purification was achieved by $(NH_4)_2SO_4$ precipitation followed by column chromatography on DEAE Sephadex A-25.