Cellulases are enzymes that act on the hydrolysis of cellulosic substrates and comprise a complex capable of hydrolyzing cellulose and producing glucose. This conversion can be performed by an enzymatic complex found in secretions of such microorganisms as fungi and bacteria. The challenge is to transform this conversion into a quicker and more cost-effective process. The objective of this study was to evaluate the activity of the cellulase produced by the fungus Pycnoporus sanguineus (L.) Murrill, strains D1-FB, D3-FB, D5-FB and D10-FB, isolated from Baccharis dracunculifolia D. C. (Asteraceae), in the production of cellulolytic enzymes. This study was conducted using sugarcane bagasse enriched with carboxymethylcellulose at 1% as a substrate. The material was kept in an incubator at a temperature ranging from 25 to 45°C for 43 days, with the cellulase activity being quantified every seven days. The indirect quantification method was employed to quantify reducing sugars that were determined by reaction with Domain Name System (DNS). After evaluation, it was observed that the fungus strain P. sanguineus (L.) (D10-FB) presented the highest cellulase activity, with values of 16.32±2.65 IU/g of fermented substrate after 29 days of fermentation, using sugarcane bagasse as the substrate, at a temperature of 30°C and pH 5.5.