To provide a compact apparatus wherein even a water containing stock material is gasified in a one cylinder once through system and is exhausted, and it provides predetermined characteristics to a solid.

A heat resistant cylindrical structure 2 is provided, which rotates around an axis 1 slightly inclined with respect to a horizontal axis or a horizontal plane, and stock supply means 6 is provided at one end of the cylindrical structure 2 for feeding a combustible stock material to be heated into the cylindrical structure 2. Stock circulation means 9, 10 are provided in a region close to the foregoing one end of the cylindrical structure in the same structure 2 for circulating the stock material axially, and an opening 11 is provided at the other end of the cylindrical structure 2 for discharging a granulated flake- like solid obtained by heating the stock. Further, a solid reaction gas introduction pipe 15 and a combustion air feed pipe 14 are disposed, protruded from the other end of the cylindrical structure into the cylindrical structure 2.