A cellulase Producing fungus aspergillus niger was mutugenized by copper vapor laser irradiation. Four mutant strains of high cellulase production were selected. When they were cultivated in straw-wheat bran solid medium at 28～30 ℃ for 96 h, the highest enzyme activities were as follows: CMC enzyme activity (Cx): 2839 mg Glucose/g·h, Filter Paper enzyme activity (CL): 299 mg Glucose/g·h, and β-gluccoidase: 1091 mg Glucose/g·h. In addition, some characteristics of No.78 strain, such as morpholopgical character, development, fementation cycle, and stability of enzyme production, were tested. These results were ideal and showed that laser matagenesis was one of the useful mutagenetic techniques newly applied to microbial breeding.