PURPOSE: To obtain a freeze-dried material of storage-stable under a relatively simple storage condition by making a microorganism-containing medium containing a bacterium keeping viability and fertility contain a carbohydrate, gelatin and ascorbic acid at a specific ratio and freeze-drying the resultant medium.

CONSTITUTION: This freeze-dried material is obtained by culturing a bacterium such as a strain of Acidophilus or a strain of Bifidobacterium in a culturing solution constituted with milk powder and a suitable nutritive agent so as the bacterium to be a stationary growing phase, and adding a carbohydrate (preferably milk sugar, etc.), gelatin, ascorbic acid in a dried weight ratio of (16/1/0.1)-(16/1/1) (preferably mixing them so as a dried weight ratio of the bacterium culturing solution, carbohydrate, gelatin and ascorbic acid to be 2/16/1/0.2) and mixed, and subjecting the resultant mixture to freeze-drying.