[en] The effect of pressures up to 1.2 GPa on saturated magnetization M _S of Ni_2+x Mn_1-x Ga (0x0.2) alloys has been studied at temperatures from 5 to 400 K. The pressure parameter, dln M _S/dp at 5 K, varies from -0.3x10^-2 GPa^-1 up to -1.3x10^-2 GPa^-1. At temperature T _M of martensitic transition (MT), dln M _S/dp changes its sign. M _S and the Curie temperature T _C of the cubic phase of compounds increase with increasing pressure. These results are consistent with a theoretical picture of band structure of Ni₂MnGa assuming a broadening and a depletion of the dominant minority Ni e_g band under pressure