UPPER THREAD FEEDING DEVICE

PURPOSE:To effectively feed threads by changing pressure to the driving roller of a slave roller corresponding to the thickness of threads. CONSTITUTION:This device is provided with a driving roller 25, slave rollers 26a and 26b arranged so as to be contacted or separated to the driving roller 25 for feeding the thread while clamping the thread with the driving roller 25, spring 30 to energize the slave rollers 26a and 26b so as to contact the driving roller 25, tensile force adjusting means to adjust the tensile force of the spring 30, thread thickness detecting means to detect the thickness of the thread, and control means, and the control means controls the tensile force adjusting means so that the tensile force adjusting means can suitably set the tensile force of the slave rollers 26a and 26b corresponding to the thickness of the thread detected by the thread thickness detecting means.