PURPOSE: In a synthetic fiber winder, to improve the spinning speed by fixing a traverse mechanism comprising a cylindrical groove cam, traverse guide, etc. to the winder body rollably in the traverse direction.

CONSTITUTION: A traverse guide 2 which slips in the endless groove in a cylindrical groove cam through the rotation of said cam 1 and guided by a traverse rail 3 will reciprocates in the traverse direction to perform the traverse motion. The housing 5 containing said traverse mechanism is rolled continuously in the traverse direction with predetermined period by the rolling drive section 9. When selecting the rolling period properly for the traverse times, the string traversed by the traverse guide 2 will disperse the string block at the end and transfered by a roll 10 without increasing the hardness to be wound on a rotating bobbin 12. Since the inverting curvature can be enlarged, the service life of the traverse guide is lengthened enabling the high speed winding.