Oxidative stress is associated with metabolite formation in fungi. In contrast to an Aspergillus niger wild-type strain, a sclerotia-formation regulator ansclR deletion strain demonstrated increased susceptibility to oxidative stress and reduced transcription of the catalase gene, catB, while an ansclR overexpression strain showed enhanced resistance to oxidative stress and increased expression of catB. In addition, ansclR complementation strain expressed a wild-type level of catB. The ansclR overexpression strain also produced the same metabolites as the wild type strain treated with H2O2. Furthermore, LC-MS, NMR, and IR analyses showed that the main metabolite was a steroid analog. Our study adds new clues to oxidative stress-related factors and metabolite formation in A. niger.