PROBLEM TO BE SOLVED: To provide a circulation type grain dryer which can be smoothly and quickly switched to discharge operation after drying operation and to cleaning operation after the discharge operation through a simple procedure involving a small number of switches.SOLUTION: A control section 38 has: a drying operation mode to automatically dry grain; a discharge operation mode to automatically discharge the grain out of a machine; and a cleaning operation mode to automatically clean the machine with no grain left in the machine. The control section 38 also has: discharge and cleaning operation means which drives circulation transport means (10, 11, 14 and 15) with a circulation-discharge switching valve 27 switched to an external discharge side in the drying and cleaning operation modes; discharge operation stop means which automatically stops the discharge operation mode when a moisture meter 26 detects a state with no grain left in the machine in the discharge operation mode; and cleaning operation
