The spectra, temperature dependence, and depolarization ratio of the quasielastic light scattering (QELS) in cubic zirconia are studied in the frequency range 0.04--1000 cm and the temperature range 300--1500 K by using a tandem Fabry-Perot interferometer. The spectral shape is found to be non-Lorentzian, which cannot be interpreted with a single relaxation time. The spectra and the temperature dependence of the intensity are fairly well explained by Ngai's dielectric relaxation theory. It is found that the ratio of the intensity of the polarized and depolarized light depends strongly on the direction of the electric vectors relative to the crystal axis. This fact suggests that a vacancy-pair mechanism is responsible for the origin of the QELS.