Poly(ethylene terephthalate) (PET) fibers with wide range of molecular orientation and crystallinity were prepared by the cold drawing of melt-spun yarns in a temperature-controlled water bath and the subsequent annealing for these samples. For all samples, the true stress-strain curves can be principally superimposed to a master curve which corresponds to the stress-strain curve for the original nonoriented amorphous yarn and it was confirmed that the original (intrinsic) network structure is not affected by molecular orientation and crystallinity significantly. Tensile properties of these fibers were studied systematically in terms of the network draw ratio which was determined as a shift factor in the matching process of a true stress-strain curve to the master curve. Consideration of the tensile drawing behavior has shown that the network draw ratio, which is defined as an extension of unique intrinsic network structure, has direct correlation with mechanical properties including the yield and breaking behaviors. When the network draw ratio is taken into consideration, PET fiber, even if it has crystallinity or molecular orientation, has appeared to behave in the manner of an almost ideal rubber during the tensile testing carried out as cold drawing.