The present invention provides a magnetoresistive (MR) element that is excellent in MR ratio and thermal stability and includes at least one magnetic layer including a ferromagnetic material M-X expressed by M.sub.100-aX.sub.a. Here, M is at least one selected from Fe, Co and Ni, X is expressed by X.sup.1.sub.bX.sup.2.sub.cX.sup.3.sub.d (X.sup.1 is at least one selected from Cu, Ru, Rh, Pd, Ag, Os, Ir, Pt and Au, X.sup.2 is at least one selected from Al, Sc, Ti, V, Cr, Mn, Ga, Ge, Y, Zr, Nb, Mo, Hf, Ta, W, Re, Zn and lanthanide series elements, and X.sub.3 is at least one selected from Si, B, C, N, O, P and S), and a, b, c and d satisfy 0.05.ltoreq.a.ltoreq.60, 0.ltoreq.b.ltoreq.60, 0.ltoreq.c.ltoreq.30, 0.ltoreq.d.ltoreq.20, and a=b+c+d.