To simplify the manufacturing process of fermented milk and to obtain crystalline saccharides having function exhibiting a physiological effect on living things by subjecting lactobacillus or the like to secondary fermentation.

The crystalline saccharides are obtained by cultivating lactobacillus (containing bifidus bacillus) and butyric acid bacteria in a liquid medium containing skim milk as nutrient by treating the culture solution in which the proliferation of lactobacillus or the like is finished through subjecting the solution to the filtration with filter cloth or filter paper or to centrifugation to remove solid matters, by concentrating the resultant solution through vaporizing humidity and by subjecting the purine- like product to secondary fermentation through allowing it to stand in a wet state so as to form radial or amorphous crystalline substances, followed by separating and recovering these crystalline substances through washing with cold water, by subjecting them to treatment using activated carbon and activated clay and by filtering the product through precise filtration membrane or ultrafiltration membrane. The resultant filtrate is dried and purified to obtain crystalline saccharides which are used singly or in a blended state among a plurality of lots, to prepare foods, fodder and drugs.