L-threonine is produced by aerobically culturing a bacterium belonging to the genus Acinetobacter, which utilizes ethanol and has an ability to produce and accumulate L-threonine, in a culture medium in which ethanol is the main carbon source to produce and accumulate L-threonine in a culture liquor and recovering L-threonine from the culture liquor. The bacterium is preferably a mutant of Acinetobacter calcoaceticus YK-1011 (Ferm-P No. 5910).