PURPOSE: To utilize a cooling tank to cool and receive raw unhulled rice by providing a grain transfer line from a first circulation dryer through a third circulation dryer to a relay tank and a grain transfer line from the relay tank through the first and third circulation dryers.

CONSTITUTION: Raw unhulled rice is supplied to a tempering tank of a first circulation dryer 7 to effect the first drying of rice and the dried rice is circulated to the tempering tank. The raw unhulled rice in the dryer 7 undergoes the second drying to be circulated to the tempering tank. The dried unhulled rice undergoes the third drying and is circulated, then undergoes the fourth drying and thereafter is transferred and stored in a relay tank 34 via a transfer line (x) and a lift 35. By utilizing a lift of the dryer 7 which is not in operation, raw unhulled rice is fed to a cooling tank 11 to dry it only one time and the rice is returned to the tank 11. The dried rice in the tank 34 is returned to the dryer 7 via a transfer line (y) to be subjected to the fifth drying and temporarily stored, with a burner being out of operation, after which the rice is transferred to the tank 34, then to a rice huller 38. The other circulation dryers are operated in a similar manner.