Bifidobacterium bacteria, called probiotics, have been reported to exhibit various physiological functions such as positive effects on the human digestion system. A number of products containing the bacteria have been put on the market in the form of fermented milk products.  In order to get sufficient effects in the large intestine, Bifidobacterium bacteria must be the viable form.  But the consumer cannot find products that listed the number of viable cells on the label, except for foods for specified health uses “tokuho”.  Therefore, we carried out the viable count of bacteria in yogurt and drink yogurt (12 items from 8 companies in Japan ) to find a fermented milk product having a high bacterial viable count and high viability during storage after production. As a result, the fermented milk food and drink contained 3×10⁶ to 4×10⁸ cfu/g or ml, and their viabilities during chilled storage were different.  Of these products, the drastic reduction in the viable cells was started in a yogurt after two weeks from the manufacture.  The improvement for maintaining a high viable cells during shelf life was completed, and in some yogurts, no decrease in the viable cells was observed for 1 month when the storage temperature was maintained at 4°C. Also, regarding the tolerance of Bifidobacterium bacteria against artificial digestive fluids in vitro, a difference existed between the manufacturers.