a process for producing a ultrafine fiber such that each two adjacent component filament phases are separated by a separator phase which is afterwards removed in such divisional spinning processes the use of special nozzles are essential but their advantage is that ultrafine fibers true to specifications can be easily obtained the cross section of the spun fiber may be freely selected thus the fiber may be a honeycomb or radiant structure a side by side structure or a flower stamen petal structure for instance wherein components c and b are alternately arrayed any desired sectional configuration can be obtained by selecting the proper nozzle geometry and the proper feeding pattern for components c and b taking the honeycomb structure as an example there is known a spinning method using a nozzle such that component c is extruded from a multiplicity of inwardly disposed orifices and component b is extruded enternally thereof so as to surround component c the term blending as used herein means that a pre blend of components c and b is extruded from a spinneret nozzle of the conventional design even in such a blending process the island or islet phase component c is stretched at such a high draft ratio that the.