The morphological change and molecular orientation of electrospun ultrafine poly(ethylene terephthalate) (PET) fibers were investigated during uniaxial drawing. The average diameters of the ultrafine PET fibers electrospun from 8, 10, and 12 wt% PET solutions were 220, 450, and 1600nm, respectively. The ultrafine PET fibers were drawn inhomogeneously with multiple necking deformations at $25^{circ}C$, whereas they could be homogeneously drawn without necking at $75^{circ}C$. The orientation of the PET chains in the ultrafine PET fibers readily proceeded when drawn at $25^{circ}C$ via necking deformation. By comparing the fractions of the trans conformer of the ultrafine PET fibers and the amorphous PET films (ref. 14, 15), it was found that the orientation of PET chains more readily proceeded in the ultrafine PET fibers than in the amorphous PET films.