To enable the rotation speed of a motor for driving a blower to be controlled without using an additional device such as a sensor, enable the rotation speed of the motor for driving the blower to be controlled while supplying a minimum required negative pressure and save required energy while smoothly operating an automatic winder.

The number of yarn splicing operation of each winding unit 1 and the number of failures in yarn splicing are counted to calculate a mistake rate of the whole system. On the basis of the calculated mistake rate, an output frequency of an inverter 19 for supplying electric power to the blower motor 18 is controllably increased or reduced.