The aim of this study was strain improvement of Bacillus pumilus for Carboxy Methyl Cellulase production by physical mutation (UV irradiation) and Chemical mutation (Ethyl Methyl Sulphate).The wild Bacillus pumilus strain isolated from earthworm gut produced 0.665 ± 0.004 IU/ml of CMCase. After UV irradiation Bacillus pumilus(UVR10) exhibited high efficiency of CMCase production (1.330 ± 0.075 IU/ml).The UV mutant Bacillus pumilus was further subjected to chemical mutation in EMS (200 μg/ml)at different time intervals. The least survival was recorded at an exposure period of 120 minutes. In this regard, Bacillus pumilus CR24 exhibited high efficiency on the basis of the CMCase production (2.610 ± 0.093 IU/ml).The mutant strain of Bacillus pumilus effectively produced higher amount of CMCase than wild Bacillus pumilus strain.