In the process of drawing/heat treating synthetic fiber thread melted and spun via a plurality of godet rollers and subsequently winding the same, accumulation of extraneous matter on the surface of the godet rollers may be prevented by performing multistage drawing/heat treatment while reciprocating the thread in the direction of the axis of rotation of the godet roller using the godet rollers at least two of which have surfaces having the roughness of 0.5nullRanull5 and one of which has a surface at a temperature of at least (melting point of synthetic fibernull70null C.), whereby occurrence of thread breakage or generation of fuzz may be prevented and synthetic fiber whereof the rate of operation can be increased and efficiency of manufacture is improved may be obtained.