Abstract: This invention provides an amorphous ferromagnetic oxide represented by the formulaA.sub.x.(MmOn).sub.y.(Fe.sub.2 O.sub.3).sub.zwherein A represents at least one of Bi.sub.2 O.sub.3, V.sub.2 O.sub.5, TeO.sub.2 and GeO.sub.2 ; M represents at least one of Mn, Fe, Co, Ni, Cu, Mg, Zn, Cd, Ca, Pb, Ba, Sr and rare earth elements; when M is not a rare earth element, m=1 and n=1; when M is a rare earth element, m=2 and n=3; O<x.ltoreq.80, O<y.ltoreq.60 and 5.ltoreq.z.ltoreq.60 and x+y+z=100, provided that when M is Co, O<x<60, O<y<60 and 40.ltoreq.z.ltoreq.60, and processes for preparing the same.