In order to develop a magnetic material for high-density magnetic recording media which overcomes the thermal agitation effect, the magnetic properties, such as saturation magnetization and magnetic anisotropy, were evaluated for Co–M (M=Pt, Pd, Ru, Rh, Os, Cr, Ge, Mo, Mn, Re, and Si) binary alloys. Ge addition was found to be effective in maintaining the value of the magnetic anisotropy field of Co. Furthermore, a ternary magnetic alloy of Co–Ge–Cr (85 at. % Co, 10 at. % Ge, 5 at. % Cr) was found to have the following magnetic properties: Kugrain ≥ 3×106 erg/cm3, Hkgrain ≈ 10 kOe, and 4πMs/Hkgrain<1.0. This magnetic material is a very promising candidate for use in high-density magnetic recording media. © 2000 American Institute of Physics.