WO₃ nanofibers were synthesized using an electrospinning method and characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The obtained WO₃ nanofibers were used as sensitive materials for the detection of NH₃. Indirect-heating sensors based on WO₃ nanofibers were prepared. When the WO₃ nanofiber-based sensors were exposed to 100 ppm NH₃ at 500 °C, the response is 5.5, and the response and recovery times are 1 and 5 s, respectively. These results indicate that the gas sensors based on WO₃ nanofibers express high and fast response and recovery characteristics to NH₃, and the WO₃ nanofibers are promising sensitive materials for NH₃ detecting.