Utilization of iron sulfide concentrate which was obtained from floatation tailing of copper and zinc ore by refloatation has been studied. To obtain high purity of iron chloride, chlorination of the concentrate was proceeded and the product was separated from other chlorides. The ultimate purpose of this study was to make magnetic iron oxide by oxidation of pure iron（III） chloride. The chlorination of the sample was examined by means of thermogravimetry, and the purity of iron(III) chloride was high. From the results, the optimum temperature of reaction was 350 ℃ and the yield of iron(III) chloride was 95 % by weight.