the polymer in the filament this second solvent content adjusting operation can be carried out in a single step by using a single aqueous washing bath or in two or more steps by using two or more aqueous washing baths the second solvent content adjusted filament is subjected to a second wet drawing operation at a draw ratio of 1 1 or more this second wet drawing operation is carried out in a single step by using a single aqueous wet drawing bath or in two or more steps by using two or more aqueous wet drawing baths the second wet drawn filament is dried and is then subjected to a dry drawing operation to an extent such that the entire draw ratio in the first and second wet drawing and dry drawing operations is in the range of from 4 0 to 7 0 the dry drawn filament is subjected to a desired finishing operation for example winding up heat setting or crimping in the first solvent content adjusting operation it is important that the content of the organic solvent contained in the undrawn filament be adjusted to a level of from 15 to 30 based on the weight of the polymer in the filament when the content of the organic solvent is less than 15 it will be difficult to satisfactorily draw the resultant filament in a washing water bath at a low temperature also if the content of the organic solvent is more than 30 the drawing procedure for the resultant filament will cause an undesirable flow of the molecules in the filament and therefore the degree of orientation of the molecules in.