Simultaneous overproduction of intracellular B-glucosidase and extracellular endoglucanase was attempted by constructing two artificial operon systems comprising the B-glucosidase-endoglucanase gene(BE) or the endoglucanase-B-glucosidase gene(EB) under the control of a strong engineered promoter, BJ27U Delta 88 and expressing them in Bacillus subtilis DB104. Two artificial operon systems contained 30 bp or 5 bp gap between the termination codon of the upstream gene and the SD sequence of the downstream gene, respectively. These operon systems were expressed well in B. subtilis and overproduced the B-glucosidase cell extract as well as the endoglucanase supernatant. The level of expression in the operon system was almost the same as that in a single expression system.