To provide a yarn supply device capable of providing required yarn tension, surely preventing winding of yarn around a peripheral face part, made approximately independently of a yarn material to be used.

This yarn supply device is at least one yarn supply unit equipped with a rotatable yarn supply drum 1 and a yarn guide device. The yarn supply drum 1 has a first peripheral face part 11a and a second peripheral face part 11b for forming friction surfaces corresponding to a yarn to be supplied and the yarn guide device has an inlet element 18 related to the first peripheral face part 11a and an outlet element related to the second peripheral face part 11b. Further the yarn supply device has two movable guide elements 20 for yarn and these guide elements 20 are related to the peripheral face parts corresponding to them. Consequently a yarn is guided between the inlet element 18 and the outlet element by the guide elements 20, is continuously treated with the first peripheral face part 11a and the second peripheral face part 11b. The device is designed and/or constituted so as to lay a yarn on the related peripheral face part at a peripheral face angle in the feeding position of the guide elements 20 larger than that in the nonfeeding position of the guide elements 20. The yarn supply device has a unit to treat the yarn differently from the peripheral face parts.