To efficiently obtain high quality drying by avoiding quality deterioration caused by the exposure of grains to be dried to a high temperature.

A mixing storage tank 10 is provided for mixing and storing the grains to be dried and a moisture absorbing material. A separation and return means 11 is provided for carrying out the mixture in the mixing storage tank 10, separating it to the grains to be dried and the moisture absorbing material, and returning the separated grains to be dried to the mixing storage tank 10. A circulation type dryer 12 is provided for mixing a moisture absorbing material with the moisture absorbing material separated by the separation and return means 11 to carry out circulation drying. A moisture absorbing material return passage 13 is formed for returning the moisture absorbing material fetched from a circulation passage of the circulation type dryer 12 to the mixing storage tank 10.