In many food industries, glucoamylase is extensively applied because of its ability to convert oligosaccharides into glucose. Recently, mutagenic treatments of Aspergillus awamori have been conducted to improve and enhance glucoamylase production. This research was focused on the study of glucoamylase production by strains of A. awamori after being exposed to ultra-violet (UV) irradiation. The parental strain was cultivated on the PDA plates and treated by exposing under UV lamp from 0 to 90 minutes with the time intervals of 30 min. Solid state fermentation was carried out to produce glucoamylase using cassava peel as a substrate. As compared to all strains, the mutant strain of A. awamori after being treated by 30 min of UV exposure time gave the highest activity of glucoamylase at 5.9 U/ml. The activity was two fold higher than the parental strain. The same mutant strain also reached its maximum value of total protein content at 97.31 µg/ml and 23% higher than parental strain. Glucoamylase production can be achieved and improved by the strain of A. awamori after UV mutagenic treatment.