Mechanical loss (internal friction) in cubic zirconia was measured in the flexural mode in order to understand the local structure associated with oxygen vacancy. Polycrystal and single crystal with different orientation of longitudinal axis ([100], [110], [111]) were adopted from 8 mol-% Y2O3 stabilized zirconia (8Y-FSZ), which shows that the internal friction profile depends on crystal orientation. In the present study, furthermore, anelastic strain behavior was also investigated in the single crystal specimens. Anelastic strain productivity is also strongly dependent on crystal orientation like internal friction: [100] < [110] < [111]. It is considered that the crystal orientation dependence of internal friction and anelasticity is closely correlated with the behavior of cation-oxygen vacancy complexes. Finally, the mechanism of anelasticity was discussed.