Electron transitions between magnetic anisotropic impurity centers in garnet crystal lattice under the influence of elliptically polarized light are considered. The theoretical model of the occupancies kinetics of such centers was developed. Spatially inhomogeneous distribution of the energy of photoinduced magnetic anisotropy was calculated in the sample being illuminated with light with modulated polarization. A conclusion about a possibility of recording of holographic magnetic gratings in the investigated materials was made depending on results obtained.