Recent experiments [1,2] showed that the ferromagnetic shape memory alloys (SMA) have some perspectives to generate the significant magnetic field induced deformations. Taking into account the high mobility of the twin boundaries of martensite crystal lattice variants, the corresponding magnetic measurements were performed with using the SMA Ni-Mn-Ga and Fe-Pd. The large strains were found in martensite and austenite phases. The Ni-Mn-Ga alloy high temperature phase demonstrates the enhancement of crystal lattice instability effects in comparison with nonmagnetic SMA alloys. It is concluded that the condensation of the soft acoustic phonon mode TA2 (q = 1/3 < 110 >) takes place at T = Ti >Ms in Ni-Mn-Ga alloy (M-s - martensite start temperature). Magnetic property anomalies accompany this phase transition which can be interpreted as a transition to an intermediate phase. The characteristic temperatures M-s and T-i are close in some alloys. The simultaneous action of the lattice instabilities connected with the formation of martensite and intermediate phases produces the essential decreasing of the elastic constants and as a result the strong growth of the high temperature phase magnetostriction nearly at T=M-s.