The investigation of magnetic properties of diluted ferrite NiGa0.8Al0.8Fe0.4O4 is carried out. Anomalous behaviour of spontaneous magnetization σs(T), coercive force Hc(T) and volume magnetostriction ω(T) is revealed for the sample with frustrated magnetic structure. It is found that volume magnetostriction ω reaches very large (that is to say “giant”) values (ω ~ 5•10–4) (for T = 84 K). It is revealed that the derivative dω/dH is equal ≈ 43 • 10–9 Oe–1 (for T = 84 K). The assumption is made that the size of clusters is about 3 nm in the spin glass phase (for Tt < T < TC).