PURPOSE: To prevent a clogging of the grains by providing a grain amount detector between a horizontal spiral conveyor and a bucket conveyor and opening/closing a shutter of a hopper in accordance with the detected value.

CONSTITUTION: About a grain feeder controller unit feeding the grain to a conveyor of a grain adjustment processor. The grain is fed to a horizontal spiral conveyor 8 from a chute 9 of a hopper through a shutter 11 to transport them in a horizontal direction, thereafter to be fed to a bucket conveyor 20 via a connecting portion. At the connecting portion is provided detector 18 to make a swing motion when the grains gather too much between both conveyors for a limit switch 21 to operate a solenoid 22 to eventually close the shutter 11 upon detection of the swinging motion so that an over-loaded grain feed onto the bucket conveyor can be prevented.