Shape memory effect and superelasticity are studied in this paper. At room temperature, perfect strain plateaus of 3.3%, 2% and 3% are obtained in the [001], [110] and [111] directions. The energies required to induce the martensitic transformation in different crystallographic directions are estimated from the stress-strain results. Each of the magnetization curves in the martensitic phase indicates that a magnetic anisotropy energy density Ku = (1/2)MsHa =4.8× 105 erg/cm3, which is far smaller than the mechanical driving force for variants twinning. This interpretes why only a little magnetic field induced strain in NiFeGa alloy has been observed so far.