Dwarf spheroidal (dSph) galaxies are ideal sites for studying the basic properties of dark matter halos, because such galaxies are largely dominated by dark matter, with mass-to-light ratios of 10 to 1000. Until now, most of mass models for dSphs have assumed spherical symmetry for simplicity, so the detailed comparisons with CDM models have yet been limited. However, luminous parts of dSphs are actually non-spherical and CDM models predict non-spherical virialized dark halos. We thus construct non-spherical mass models for dSphs to obtain more realistic and important limits on density profiles and shapes of dark halos. We first construct axisymmetric mass models based on the axisymmetric Jeans equations, where each of visible and halo density profiles has an axis ratio, and we also take into account a finite inclination angle with respect to the line of sight. Based on these models, we find characteristic features in the profiles of line of sight velocity dispersions for axisymmetric mass models and the application of these models to six dSphs in the Galaxy reveals that shapes of their dark halos deviate significantly from spherical symmetry.