The invention is directed to an apparatus for drying powdered or granular materials comprises a drying tank (1) including a transversely extending drying room (7) adapted to be applied with heating by microwaves, at least one partition (20) defining more than two drying zones in the drying room (7) of the drying tank (1), a rotary shaft (12) disposed in the drying tank (1) in its longitudinal direction to extend through the drying room (7) in a manner of being freely rotatable and agitating blades (30a), (30b) . . . provided on the rotary shaft correspondingly to each drying zone, microwave application units (40) provided for each drying zone, and temperature sensors (50) for each drying zone and corresponding temperature adjusters (51) connected to the respective temperature sensors (50).