PURPOSE: A yarn of synthetic multifilaments is passed through a spinning chimney of specific shape and wound up at a high speed to make it unnecessary to invest a large-scale facility and solve the problem on the troubles caused by the air flow accompanying the high-speed running yarn.

CONSTITUTION: A yarn of synthetic multfilaments such as polyamide or polyester multifilaments is passed through the spinning chimney of a shape satisfying equation I [S1 is the opening area in cm2 at the top of the chimeny; N is the filament count of the yarn passing through the chimney], equation II [S3 is the opening area in (cm2) at the bottom of the chimney] and equation III (Q is the tapering angle in degree at the tapered part of the cimney bottom), then wound up at a high speed, preferably 3,000m/min, thus eliminating the troubles caused by the air stream accompanying the high-speed yarn running without large-scale investment for facilities.