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A ferromagnetic shape memory alloy of Ni 48 Mn 30 Ga 22 prepared by induction melting was successfully hot forged. Strong textures and a large anisotropy of in plane plastic flow were developed during the hot forging process. The crystal structures, both in austenitic and martensitic states, were investigated by means of neutron powder diffraction technique. The result suggests that Ni 48 Mn 30 Ga 22 has a cubic L2 1 Heusler structure at room temperature, the same as that in the stoichiometric Ni 2 MnGa. When cooled to 243 K, the Ni 48 Mn 30 Ga 22 alloy changes into a seven layered orthorhombic martensitic structure. No substantial change of the neutron diffraction pattern was observed upon further cooling to 19 K, indicating that there is no intermartensitic transformation in the investigated alloy, which is different from the transformation processes in the Ni2Mn2Ga alloys with higher martensitic transformation temperatures.