Bacillus licheniformis alpha which was recently isolated from soil produces a novel acid-stable and thermostable alpha-amylase. The optimum pH and optimum temperature of the amylase were 4.5-5.3 and around 90-degrees-C, respectively. In the presence of Ca2+, the optimum temperature was observed at around 100-degrees-C. Under conditions in which a starch slurry (pH 4.5) was incubated with the amylase for 5 min at 105-degrees-C (the primary liquefaction) and further incubation of the primary liquefied starch for 0.5-6 h at 90-degrees-C to promote dextrinization with the remaining amylase activity (secondary liquefaction) was carried out, liquefied starch having pH and DE values which are suitable for saccharification with glucoamylase from Aspergillus niger, was obtained.