Friction is an important characteristic of the technical yarn. An understanding of this phenomenon is essential for controlling the properties of yarn in a manufacturing process. In order, to evaluate its wear behavior, the mechanical property and the friction coefficient of the yarn used in the seat belt fabric were measured. Different types of technical polyethylene terephthalate(PET) yarns were prepared by varying the yarn denier and the diameter of constituent filaments in the yarn (commonly used as denier per filament or DPF). This was done using a conventional spin-draw melt spinning machine. The yarn of a low DPF showed a higher friction coefficient than that of a high DPF. In a wear test of yarn-to-metal, the low denier yarns lost less strength than high denier yarns. To enhance the wear performance of the seat belt fabric on the basis of the yarn property, the mechanical strength and the wear property of the yarn were coincidently evaluated. As the strength of the seat belt fabric was estimated by using the results of the strength retention ratio after the wear test, a yarn type may be optimally suggested for better wear performance of the seat belt fabric.