A hopper dryer for drying pelletized or granular resin material comprising a heat source at its center and double concentric cylinders which comprises an inner and an outer cylinder with many apertures to permit passing of heated gas respectively so as to form a doughnut-like material storing space therebetween. The gas is fed into the heat source to be heated, then passes through the apertures of the inner cylinder and discharged through the apertures of the outer cylinder so that the pelletized or granular resin material stored in the doughnut-like space formed between the inner and outer cylinder are preheated and dried.
