The distribution of nickel and minor elements such as chromium, manganese, cobalt and copper between the Fe–Ni alloy and the FeO_X–MgO–SiO₂ base slag in a magnesia crucible was studied at 1773 and 1873 K under controlled partial pressure of oxygen in a range between 1.8×10⁻⁵ and 3.2×10⁻² Pa using CO–CO₂ gas mixtures. The effect of adding lime (CaO/SiO₂ molar ratio of about 1) and alumina (AlO_1.5/SiO₂ molar ratio of about 0.25) to the plain FeO_X–MgO–SiO₂ slag was also investigated. The distribution ratios of chromium and manganese, defined by (mass%X in slag)/[mass%X in alloy] where X is the minor element, for the plain slag at 1773 K have large values greater than 100 and 1000, respectively. These are 4 and 5 orders of magnitude larger than that of nickel, while those of cobalt and copper are of a magnitude similar to that of nickel. It was clarified that the addition of lime reduces the distribution of chromium and manganese into the slag while the addition of alumina increases the dissolution of chromium though it reduces the dissolution of nickel, cobalt and copper.