Abstract: Disclosed is a preparation method of a polymer composite using a giant magnetostrictive material, which is advantageous in that electric resistivity and magnetostrictive strain are increased while the unidirectionally solidified texture in the material is maintained as it is. The method consists of removing the rare earth or the eutectic phase from a unidirectionally solidifed rare earth giant magnetostrictive material; and infiltrating a polymer resin to the rare earth or cutectic phase-removed void, followed by curing the infiltrated resin. Thereby, there can be provided the polymer composite, which is advantageous in that eddy current loss is decreased due to increased electric resistivity, and magnetostrictive strain is improved as well as fracture resistance is higher due to the soft and tough properties of polymer.