Provided is a cultured milk manufacturing method with which taste and quality can be kept constant regardless of the lactic acid bacteria or enzyme conditions. The cultured milk manufacturing method comprises a fermentation process to ferment raw milk that contains an enzyme, and a deoxygenation process that is carried out prior to the fermentation. The enzyme exhibits optimal pH for activation in the neutral region and is inactivated in the acidic region, and the enzyme can break down lactose contained in the raw milk while in the active state. As demonstrated with working examples, by carrying out the deoxygenation process prior to the fermentation, the taste and quality of the cultured milk can be kept constant regardless of the lactic acid bacteria or enzyme conditions.
