STA1 gene of S. diastaticus encodes extracellular gluc glucoamylase I. The expression of STA1 gene is known to be regulated by glucose and STA10 which is known as a repressor gene in S. diastaticus. To study the regulation mechanism, we investigated the glucose effect and STA10 repression. Our data suggest that STA1 is glucose repressible rather than starch inducible, that is, the expression of STA1 gene is followed by derepression process. And the repression by STA10 was independent of carbon source. It seems that the function of STA10 is involved in inhibition of derepression process. To elucidate the existence of upstream promoter elements involved in STA1 gene expression, we constructed 5’- deleted mutant genes. By introducing these mutant genes to S. diastaticus and S. cerevisiae strain, we localized UAS and URS regions which were independent of glucose and STA10.