The fungus, CM5, showed the highest decolorized of molasses wastewater from 16 isolated fungi. CM5 decolorized molasses wastewater 49.19% in 30 days, media containing 10% molasses wastewater and 2% malt extract powder. CM5 was induced mutation by ultraviolet irradiation. The mutant strain, UV—2 showed the highest decolorized of molasses wastewater that decolorized 48.30% in 8 days, media composed of 10% molasses wastewater 0.1% glucose 0.1% Glucose 0.1% K₂HPO₄ 0.05% MgSO4•7H₂O 0.05% KCI 0.001% FeSO₄•7H₂O 0.0001% ZnSO₄•7H₂O 0.0001% MnSO₄•5H₂O 0.0001% CuSO₄•5H₂O, that wild type strain decolorized 31.42%. UV—2 enhanced resistant for malachite—green compared with wild type but it highly sensitive in ketoconazole. UV-2 mutant was induced mutation by MNNG then generated many UV-NG mutants. UV2—NG10 mutant was the greatest decolorizing molasses wastewater mutant that showed 84.15% decolorized in 8 days compared with wild type. No difference in ITS region restriction enzyme DNA pattern was detected from Alul HinƒI and Mbol.