Provided is the production of a skim milk starting material milk, said production having no risk of affecting the flavor of the cheese, having low energy consumption, having no risk of bacteria accumulating within a centrifugal separator, increasing the bacteria elimination rate of the centrifugal separator, and not requiring a large capacity centrifugal separator. [Solution] The present invention is provided with a first centrifugal separator (3) that separates milk (1) into a cream fraction (5) and a skim milk fraction (6)； a microfilter (11) that separates the skim milk fraction (6) into a permeate (14) and a retentate (15)； a second centrifugal separator (18) that separates the retentate (15) into a clean fraction (20) and a high bacteria content sludge (21)； and a means for returning the clean fraction (20) to the microfilter (11), and the permeate is provided as the skim milk starting material milk (26).
