The present invention relates to a yoghurt with promoted growth of Lactobacillus bulgaricus and its production method for relatively promoting the growth of Lactobacillus bulgaricus and relatively inhibiting the growth of Streptococcus thermophilus. The production method of yoghurt according to the present invention comprises a sterilization step for sterilizing the raw milk； a cooling step for cooling the raw milk which has been heated and sterilized； a starter addition step for adding a lactic acid bacteria starter containing Lactobacillus bulgaricus and Streptococcus thermophilus into the raw milk during the cooling step or after the cooling step to obtain a yoghurt base material； a low temperature maintaining step for maintaining the yoghurt base material after the starter addition step under a temperature lower than the fermentation promotion temperature； a heating step for heating the yoghurt base material, after the low temperature maintaining step, to a fermentation promotion temperature； and a fermentation step for fermenting the raw milk, after the heating step, to obtain the yoghurt.本發明關於促進保加利亞菌繁殖的酸乳及其製造方法，係可相對地促進保加利亞菌的繁殖，且相對地抑制嗜熱菌的繁殖，而有關本發明之酸乳的製造方法，其包含將原料乳進行殺菌的殺菌步驟；將加熱殺菌步驟後之原料乳進行冷卻的冷卻步驟；於冷卻步驟中或冷卻步驟後之原料乳添加包含保加利亞菌與嗜熱菌之乳酸菌菌元而得到酸乳基材的菌元添加步驟；將菌元添加步驟後之酸乳基材保持於低於促進發酵溫度的低溫保持步驟；將低溫保持步驟後之酸乳基材進行加溫至促進發酵溫度的加溫步驟；及使加溫步驟後之原料乳進行發酵，而得到酸乳的發酵步驟。
