An air capacity controlling method for a centralized blower system wherein a common suction air duct is connected to a plurality of winders such that suction air for operation may act upon the winders through the duct, and a preset number of suction blowers having a total air capacity corresponding to a total air quantity necessitated by the winders are connected in a parallel relationship, is constituted such that it is detected from a pressure of air within the duct that the total air quantity necessitated by the winders has varied, and the air capacity of the suction blowers is adjusted in accordance with such a detection value.