[Problem] The purpose of the present invention is to provide a method that is for producing a fermented milk and that can maintain flavor and quality at a certain level regardless of the condition of lactobacilli or an enzyme. [Solution] The present invention relates to a method for producing a fermented milk, said method containing a fermentation step for fermenting a starting material milk containing an enzyme, and a deoxygenation processing step performed before fermentation. Also, the optimum pH of activity of the enzyme is in the neutral region, and the enzyme is inactivated in the acidic region. In the active state, the enzyme can break down lactose contained in the starting material milk. As demonstrated by an embodiment, by performing deoxygenation processing before fermentation, it is possible to maintain the flavor and quality of the fermented milk at a certain level regardless of the condition of lactobacilli or the enzyme.
