A spinning machine comprising: a plurality of spinning units each including an air-jet spinning device configured to perform spinning operation of twisting a fiber bundle with air to generate yarn and a winding device configured to wind the yarn around a bobbin to form a package; an air pipe configured to allow the air to flow therethrough and connected to upstream sides of a plurality of feeding pipes through which the air is supplied to the respective air-jet spinning devices of the spinning units; a feeding device configured to feed an additive to the air pipe; and a control device configured to control operation of the feeding device, wherein when an operating number that is the number of air-jet spinning devices being operating among the air-jet spinning devices is smaller than a predetermined number, which is a predetermined fraction of or a number smaller than the total number of the air-jet spinning devices installed, the control device is adapted to control the feeding device such that the additive is fed by intermittent control, this means control of alternately opening and closing an adjusting valve of the feeding device, during an intermittent cycle period, so as to increase the amount of the additive to be fed as the operating number increases or reduce the amount of the additive to be fed as the operating number decreases, and when the operating number is equal to or greater than the predetermined number, the control device is adapted to control the feeding device such that the additive is continuously fed, and when the operating number is smaller than the predetermined number, the control device is adapted to set the amount of the additive to be fed by controlling a duty ratio between an ON-period and an OFF-period of the adjusting valve based on a relation expressed by the formula: the ON-period / the intermittent cycle period = the operating number / a planned operating number that is the number of air-jet spinning devices 7 planned to be operated among the air-jet spinning devices 7, and when the operating number is equal to or greater than the predetermined number, the control device sets the amount of the additive to be fed based on the planned operating number of the air-jet spinning devices and an optimum amount of the additive that is an amount optimum for one air-jet spinning device. a plurality of spinning units each including an air-jet spinning device configured to perform spinning operation of twisting a fiber bundle with air to generate yarn and a winding device configured to wind the yarn around a bobbin to form a package; an air pipe configured to allow the air to flow therethrough and connected to upstream sides of a plurality of feeding pipes through which the air is supplied to the respective air-jet spinning devices of the spinning units; a feeding device configured to feed an additive to the air pipe; and a control device configured to control operation of the feeding device, wherein when an operating number that is the number of air-jet spinning devices being operating among the air-jet spinning devices is smaller than a predetermined number, which is a predetermined fraction of or a number smaller than the total number of the air-jet spinning devices installed, the control device is adapted to control the feeding device such that the additive is fed by intermittent control, this means control of alternately opening and closing an adjusting valve of the feeding device, during an intermittent cycle period, so as to increase the amount of the additive to be fed as the operating number increases or reduce the amount of the additive to be fed as the operating number decreases, and when the operating number is equal to or greater than the predetermined number, the control device is adapted to control the feeding device such that the additive is continuously fed, and when the operating number is smaller than the predetermined number, the control device is adapted to set the amount of the additive to be fed by controlling a duty ratio between an ON-period and an OFF-period of the adjusting valve based on a relation expressed by the formula: the ON-period / the intermittent cycle period = the operating number / a planned operating number that is the number of air-jet spinning devices 7 planned to be operated among the air-jet spinning devices 7, and when the operating number is equal to or greater than the predetermined number, the control device sets the amount of the additive to be fed based on the planned operating number of the air-jet spinning devices and an optimum amount of the additive that is an amount optimum for one air-jet spinning device.