In this study, bioethanol was separated and concentrated by a pervaporation system, and the residue was subsequently evaluated for antioxidant activity. The hydrolysate contained high acetic acid, furfural, and total phenolic compounds (TPC) as fermentation inhibitors. The bioethanol was produced from the electrodialysis-treated hydrolysate, with sulfuric and maleic acid (14.00 g/L and 13.33 g/L, respectively). The amount of TPC in the ethyl acetate extract of the residue, generated from the ethanol pervaporation after the fermentation of the maleic acid hydrolysate (MA-F-E), was as high as 100.78 mg/100 g. The IC50 values of the DPPH and ABTS radical scavenging activities and the EC50 value of the reducing power were the lowest with the MA-F-E at 0.85 mg/mL, 0.73 mg/mL, and 0.54 mg/mL, respectively. Among the phenolic compounds, vanillic alcohol, benzoic acid, and 3-vanil-1,2-propane were the most abundant compounds in the ethyl acetate extracts of the residue.