PROBLEM TO BE SOLVED: To properly dry various kinds of grains by properly controlling a hot air temperature near termination of drying by lowering the hot air temperature corresponding to reduction of bulk density of each kind of grain due to the progress of a drying operation in a circulation type grain dryer.SOLUTION: In a grain dryer including a combustion burner (7) producing hot air, a hot air chamber (14) through which the hot air passes, an exhaust air fan (10) sucking the hot air in the hot air chamber (14) and discharging the same to the outside of a machine, a moisture meter (53) for measuring a moisture value of the grain, and a control portion (S) for controlling a drying operation, the control portion (S) is provided with control means for sequentially lowering a combustion amount of the combustion burner (7) in accompany with lowering of the measured moisture value due to the progress of a drying operation, and in parallel therewith, increasing a reduction ratio of the combustion amount of the c
