PURPOSE: The titled multifilaments which have a cross section of an asymmetric cocoon shape where a hollow is formed through in the larger part of the cross section and a cross section area changing lengthwise, thus giving aesthetically good woven or knitted fabrics with excellent touch.

CONSTITUTION: The cross section of individual filaments is a cocoon-like shape where both lobes parted by the neck are asymmetric and the larger lobe has a through hollow. Further, the hollow part has higher orientation than the smaller dense lobe and the cross section area changes in the lengthwise direction. Such polybutylene terephthalate multifilaments are obtained by using nozzles each of which is composed of two orifices 1, 2 different in cross section area and a slit connecting the orifices 1 and 2, while the orifice 1 has a plurality of slits 1aW1c on a circumference, and extruding the melted polymer through the orifice 1 of a larger cross section area in a smaller amount than that extruded through the other orifice 2.