Bacillus stearothermophilus No. 236, an effective xylanolytic bacterium, produced an extracellular carboxymethyl cellulase when the strain was grown on xylan. The carboxymethyl cellulase was purified to homogeneity as judged by SDS-PAGE and zymogram, The carboxymethyl cellulase had a pI of 4.0, and a molecular mass of 95 kDa. The highest level of enzyme activity was observed at pH 6.5 and $60^{circ}C$. The $K_m$, and $V_{max}$ values of the enzyme to carboxymethyl cellulose were 20.8 mg/ml and $0.63 {mu}mole$/min/mg protein, respectively, The enzyme was found to act also on filter paper and xylan as well as carboxymethyl cellulose. Therefore, it is expected that this xylanolytic strain isolated from soil could be efficiently used for xylan biodegradation.