To prevent grains from being left in the shutter drum of a circulation grain drying machine supported at the lower end of grain flow-down passage at the inner drying section when rotation of the shutter drum is stopped.

When rotation of a shutter drum 4 supported at a position facing the lower end of the grain flow-down passage at a drying section while having an opening 41 split in the circumferential wall of a hollow tubular body 40 along the axial direction is stopped upon finishing a grain discharging process, it is turned two revolutions in same direction so that the opening 41 is stopped at a starting position directing upward or downward.