A magnetoresistive head is disclosed which uses a crystalline soft magnetic film as an undercoat for a giant magnetoresistive film provided with at least one pair of ferro-magnetic films opposed to each other across a nonmagnetic intermediate layer or for an anisotropically magnetoresistive film. The crystalline soft magnetic film comprises a film which has as a main component thereof at least one element selected from the group consisting of Ni, Fe, and Co and simultaneously incorporates therein at least one element selected from the group consisting of Nb, Mo, V, W, Ti, Zr, Hf, and Ta and at least one element selected from the group consisting of Cr, Rh, Os, Re, Si, Al, Be, Ga, and Ge.