PURPOSE: To increase the efficiency for the treatment of grains, by forming plural conveying faces vertically in a closed vessel, attaching scrapers to a roller chain at definite intervals, and placing the chain in a zigzag pattern along each conveying face.

CONSTITUTION: Steam is introduced into the vessel 10, and grains are charged to the inlet port 21, passed through water by the feeder 19, and dropped through the outlet port 20 on the conveying face 12. The grains are steamed with the steam passing through the steaming holes and with the steam in the vessel 10 in the course of being transferred along the conveying faces 12a, 12b by the action of the scraper 18. The steamed grains are discharged from the discharge port 27.