PURPOSE: To provide a dryer which has high heat exchange efficiency and is made small.

CONSTITUTION: The dryer is equipped with a cylindrical body 1 where a rotating shaft 8 having blades 15 and a heating jacket 19 are coaxially installed inside and outside, respectively. And an inflow port 6 for a material to be treated is provided on an upper side wall 5 of the cylindrical body 1 and simultaneously an exhaust port 7 is provided above the inflow port 6 for a material to be treated and further an outflow port 6a for a material to be treated in the bottom part of the body 1. And a distribution ring 16 is installed in a part of the rotating shaft 8 corresponding to the inflow port 6 for a material to be treated. The inner peripheral surface of the cylindrical body 1 is made a flat one and simultaneously the outer peripheral surface of a peripheral wall 20 in the heating jacket 19 is made an uneven one.