Samples of system CuGa x Al x Fe 2.2x O 4 (x-0.0, 0.1, 0.2, 0.3,0.4, 0.5,0.6, 0.7) have been sintered and temperature-dependences of their spontaneous magnetization σ s , coercive force 11 c , parallel λ a and perpendicular λ⊥ magnetostrictions have been investigated. Based on the experimental data it has been concluded that in the compounds with x > 0.5 there is a transition from paramagnetic state to spin glass phase, and at still lower temperatures, a transition to frustrated magnetic phase is observed. It has been found that the coercive force of the ferrites with frustrated magnetic structure is, an order of magnitude smaller than the coercive force of the ferrites which have ferrimagnetic arrangement. Magnetostriction study has shown that in given ferrites anisotropic magnetostriction has a quite small value. Therefore it has been established that in the samples with a frustrated magnetic structure magnetic anisotropy is small. On this base we suggest a new method of obtaining ferrites with a small coercive force by creating in them a frustrated magnetic structure.