PURPOSE: To shorten the time necessary to finish discharge in the condition that grains are not pushed back to the inside of a grain drier from a discharge device and the grains are smoothly discharged by stopping and controlling an exhauster which sucks the air and exhaust it when the operation of discharging the drying-finished grains reaches near its completion.

CONSTITUTION: When the operation discharging drying-finished grains dried by a grain drier 4 outside the drier is carried out and a starting switch is operated, the drying-finished grains in the drier 4 are sent out from a storage room 16 to a drying room 11 where the grains fall down into the lower part by the rotation of sending-out valves 12 and flow down and are supplied into a grain-collecting conduit 10. When the discharge of the drying-finished grains progresses and these are no grains at the upper part of the room 10 to form cavity condition, the amount of exhausted air by an exhauster 2 which sucks and exhausts the air coming from a hot air room 13 through the room 11 and an exhaust room 14 is increased and the current value of a motor of the exhauster, which rotates and drives the exhauster 2, rises up. When the current value rises up over a specified value, the motor of the exhauster is automatically stopped and controlled and the exhauster 2 is also stopped and controlled and the discharge operation of the drying-finished grains is carried out in the condition that the air is not sucked and exhausted.