PURPOSE: To expedite an efficient drying by circulating a relatively low temperature hot air by providing a conveying roller for transferring a material to be dried, a fan for circulating the air in a dryer, and a heat exchanger for heating the air circulating in the dryer, and drying the material while feeding the material, thereby simplifying an overall dryer. CONSTITUTION: Three stages of upper and lower sets of rollers 14 for constituting a conveying mechanism are arranged. Heater coils 11S are arranged above and below the rollers 14, and a heat source such as steam or the like is introduced. The air in the dryer urged by a fan 13 is heated by passing a heat exchanger 17 and the coils 11S while repeatedly circulating in a direction of arrows O, P, Q, R, S and T, while a material to be dried is bathed with the hot air to be sequentially dried while being sequentially conveyed. A far infrared ray having a wavelength of 2.5 micron or more is radiated from a heater coil arranged separately to a unit drying section 11. And the material is emitted with the ray from front and rear surfaces to bring about an electromagnetic resonance, thereby further expediting the drying by self-heating.