PROBLEM TO BE SOLVED: To produce fermented milk containing lactic acid bacteria and bifidobacteria while increasing and maintaining the viable count of bifidobacteria by a simple method. SOLUTION: A method for producing fermented milk in which a first step of mixing raw milk, lactic acid bacteria, and bifidobacteria and a second step of fermenting raw milk are performed, wherein the second step includes One or more selected from before the first step, substantially simultaneously with the first step or after the first step, having a step of adding lactase to the raw material milk (lactase adding step) before finishing. The method for producing fermented milk, characterized in that the lactase addition step is performed at the timing. [Selection] Figure 1【課題】 簡便な方法でビフィズス菌の生菌数を増大・維持させながら、乳酸菌とビフィズス菌を含む発酵乳を製造することを目的とする。【解決手段】 原料乳と、乳酸菌と、ビフィズス菌と、を混合する第１工程と、原料乳を発酵させる第２工程と、を順次行う発酵乳の製造方法であって、上記第２工程が終了する前に、原料乳にラクターゼを添加する工程（ラクターゼ添加工程）を有し、前記第１工程の前、前記第１工程と略同時又は前記第１工程の後から選択される１つ以上のタイミングで、前記ラクターゼ添加工程を行うことを特徴とする発酵乳の製造方法。【選択図】図１
