Shortening the fermentation time at the time of manufacture of fermented milk (acceleration of fermentation), and suppression of the increase in acidity during refrigerated transport and refrigerated storage of fermented milk are simultaneously achieved by a simple method. Manufacture of fermented milk immediately before or after blending lactic acid bacteria starter into raw milk or at the same time blending lactic acid bacteria starter into raw milk and blending a predetermined amount of live propionic acid bacteria into raw milk or fermented milk base A method, a method for shortening the fermentation time during the production of fermented milk, and a method for suppressing an increase in sourness. 発酵乳の製造時における発酵時間の短縮（発酵の促進）、及び発酵乳の冷蔵輸送中や冷蔵保存中における酸味の上昇の抑制を簡便な方法で同時に達成する。 乳酸菌スターターを原料乳に配合する直前や直後、あるいは乳酸菌スターターを原料乳に配合するのと同時に、所定量のプロピオン酸菌の生菌体を原料乳または発酵乳基材に配合する発酵乳の製造方法、発酵乳の製造時における発酵時間の短縮方法、酸味の上昇の抑制方法である。
