Among the microorganisms, the filamentous fungi, as a group, have contributed much to biotechnology particularly for the production of enzymes and antibiotics and continue to have considerable potential for further exploitation as producers of new products. Few research groups have developed fungal expression systems using specific host strains like, Aspergilus sojae, but their promoters are already under IPR protection. Availability of expression vector is a prerequisite in developing expression system and for that strong promoters are needed. There, however, are no reports on the catR promoter or its use in expression systems. Therefore, its promoter is a legitimate target for cloning and exploitation. This is the first report describing the identification of the regulatory element of catR gene in Aspergillus niger. Clarifying the specific induction or repression of the catR promoter provides the possibility for utilization of this promoter in industry. Finally, a finely controlled promoter can be used in studies of functional characterization of essential genes.