PURPOSE: To obtain a raw material for low-class distilled spirits free from greasiness at the end of steaming and a characteristic smell of rye, by preheating polished rye grains of raw material while transporting the grains, heating and stirring the grains in a heating duct equipped with stirring plates to gelatinize.

CONSTITUTION: For example, polished rye grains (a) are dropped from a hopper 1 on a preheating duct 3 and transported a screw conveyor 4. After preheating, the grains are sent to a heating duct 8 and transported to the downstream side while agitating stirring plates 18. High-temperature air is sent from a combustion chamber 20 to the interior of the ducts 8 and 9, the polished rye grains (a) are heated and gradually gelatinized. Successively, the grains are sent to a cooling column 22, cooled with air, transported to a given position by a conveyor 25 and used as a material for low-class distilled spirits.