A shredding and fluidization drying apparatus for treating a material such as waste paper of industrial waste generally comprises a vertical fluidization drying column, a separator for separating a dried material and a gas component fed from the fluidization drying column, a paddle mixer mixing a new material with a part of the dried material from the separator, a conveyor for feeding the mixed material into the fluidization drying column, and a hot blast supplying means for supplying a hot blast into the fluidization drying column. A pair of rotary drum assemblies, each comprising a pair of rotary drum units provided with blade members and combined suitably, are disposed at the lower portion of the fluidization drying column and the rotary drum assemblies are supported by a pair of parallel shafts to be rotatable respectively. One of the rotary drum assemblies are positioned on a hot blast supplying side and provided with a space at a central portion of the rotary drum assemblies through which the hot blast is blown and the other one of the rotary drum assemblies is positioned on a material feeding side in the fluidization drying column and provided with spaces between both ends thereof and the side wall of the fluidization drying column.