To prevent the careless discharge of materials at the start of drying by arranging a drying chamber with a materials supplying port at one edge part of it and multiple movable discharging dampers that can be opened or closed independently from the outside at different heights to the fixed wall of the drying chamber at the other edge part of it.

The dryer main body 2 of a dryer 1 is separated to an upper and a lower parts by a perforated panel 5 extended horizontally, the upper side is formed as a drying chamber 3 and the lower side is formed as ventilating chambers 4a, 4b and 4c and multiple ventilating holes 51 opening obliquely are arranged to the perforated panel 5. Arranging a material supplying opening 6 to an edge part of the drying chamber 3 and a closed fixed wall 7 on the opposite side of it, a pair of rows of right and left movable discharging dampers 8 are arranged to the fixed wall 7 at such as the three steps of heights and can be opened and closed independently by the operation of cylinders. A coarse particles discharging damper 10 is arranged below the lowest movable discharging damper 8 and can be opened or closed by the operation of an air cylinder.