Fermentation and antimicrobial activity assay from Aspergillus fumigatus isolated from corncob has been carried out. The purpose of this study is to isolate A. fumigatus from corncoband then fermentation to produce secondary metabolites. Fermentation process was conducted using corncob as liquid medium at the temperature of 300C, agitation 150 rpm, and pH of medium 6. Antimicrobial activity assay and characterization of secondary metabolites were done by agar-diffusion methods, UV-Visible, and infrared spectroscopy method. Extraction of secondary metabolites produced using liquid-liquid extraction method. The purification of the antibacterial compound was used by preparative thin layer chromatography method. Results showed that the optimum condition of fermentation A. fumigates was of 8 days. Antimicrobial activity assay against Staphylococcus aureus, Escherichia coli and Candida albicans indicated that the antibacterial activity of isolated compounds and no antifungal activity observed. It is also found that from UV-Vis spectrophotometer result of fourth isolated compounds that had antibacterial activity showed the maximum wavelength were of 201.80nm, 202.60nm, 203.20nm and 202.00nm respectively. Infrared spectroscopy result the compound AB1and AB2 consist of OH groups, stretch C=C, C – H and C = O, while in the AB3 and AB4compounds there is a stretch of C = O.