To provide a dryer capable of making a peripheral wall hardly thermally damaged and efficiently drying overall dried objects, with respect to the dryer receiving the dried objects inside of a rotary tank, and drying the dried objects by heating the peripheral wall of the rotary tank while rotating the rotary tank.

The drum-shaped rotary tank 5 rotatable around a fixed hollow shaft 2 has a double cylindrical structure of an outer tank 12 and an inner tank 13, liquid 14 such as water and oil is filled in a spatial portion surrounded by the wall surfaces of the outer tank 12 and the inner tank 13, by such volume that a slight gap c is formed, the rotary tank 5 is rotated while heating the liquid 14 by a sheath heater 18, and simultaneously the dried objects are dried while supplying and discharging the air inside of the rotary tank through the fixed hollow shaft 2, thus the temperature of the overall peripheral wall can be uniformed and the thermal damage of the peripheral wall can be prevented.