PURPOSE: To provide a readily handleable puffed fermented soybean substance with a low moisture content, excellent in preservation quality and capable of easily regulating hardness, flavor intensity of the fermented soybeans, etc., by mixing dried fermented soybeans with grain flour and subjecting the resultant mixture to puffing treatment.

CONSTITUTION: A puffed fermented soybean substance composed of dried soybeans and grains flour is produced by a method for mixing 10-50wt.% dried fermented soybeans with 90-50wt.% grain flour (e.g. wheat flour), carrying out puffing treatment with a twin-screw extruder, etc. Furthermore, the dried fermented soybeans are produced by a method for adding and mixing fermented soybeans with common salt and an organic acid (e.g. citric, acetic or lactic acid), keeping the resultant mixture at 0-10°C for 4-5 days, then drying the mixture at 40-50°C temperature and 60-40% humidity for 2-4hr, sprinkling grain flour on the surfaces of the fermented soybeans and further drying the prepared mixture at 40-50°C temperature and 30-20% humidity for 18-22hr, etc. The amount of the dried fermented soybeans in the puffed fermented soybean substance can be regulated to regulate hardness of the puffed fermented soybean substance and flavor intensity of the fermented soybeans.