A cycle zone-drawing/zone-annealing method was applied to poly(ethylene terephthalate) fibers in order to improve their mechanical properties. An apparatus used for this treatment was assembled in our laboratory. The cycle zone-drawing (cyZD) treatment was carried out in three steps. The first cyZD treatment was carried out at a drawing temperature of 90 degrees C under an applied tension of 8.7 MPa, the second at 90 degrees C under 209 MPa, and third at 130 degrees C under 366 MPa. The number of cycles in each cyZD was 5. Subsequently, the cycle zone-annealing treatment was applied to the cycle zone-drawn fiber and carried out at an annealing temperature of 210 degrees C under 281 MPa at the cycle number of 50. The fiber obtained finally had a birefringence of 0.255 and a degree of crystallinity of 55%. This fiber exhibited a tensile modulus of 15.1 GPa, tensile strength of 1.2 GPa, and a storage modulus of 24.3 GPa at 25 degrees C.