The gene encoding Schwanniomyces occidentalis $alpha-amylase$(AMY) was introduced into Saccharomyces cerevisiae var. diastaticus which secreted only glucoamylase, by using a linearized yeast integrating vector to develop stable strains with a capability of secreting $alpha-amylase$and glucoamylase simultaneously. A dominant selectable marker, the geneticin(G418) resistance gene (Gt^r$), was cloned into a vector to screen wild-type diploid transformants harboring the AMY gene. The amylolytic activities of transformants were about 3-7 times higher than those of the recipient strains. When grown in nonselective media, the transformants with the linearized integrating vector containing the AMY gene exhibited almost all of the mitotic stability after 100 generations.