The precipitation reaction is preferably performed by adding dropwise each of the solution containing Sm and Fe and the precipitating agent to a solvent such as water because this allows for easy adjustment of the properties of the particles of the precipitate. A precipitate having a uniform distribution of the constituent elements, a sharp particle size distribution, and a uniform powder particle shape may be produced by appropriately controlling conditions such as the feeding rates of the solution containing Sm and Fe and the precipitating agent, reaction temperature, reaction solution concentration, and pH during the reaction. The use of such a precipitate improves the magnetic properties of the final magnetic powder. The reaction temperature may be 0 to 50° C., preferably 35 to 45° C. The reaction solution concentration is preferably 0.65 mol/L to 0.85 mol/L, more preferably 0.7 mol/L to 0.85 mol/L, calculated as total metal ion concentration. The reaction pH is preferably 5 to 9, more preferably 6.5 to 8.

From a magnetic property standpoint, the solution containing Sm and Fe preferably further contains La, W, and/or Co. The La source is not limited as long as it is soluble in a strongly acidic solution. From an availability standpoint, for example, it may be LaCl₃. The concentration may be appropriately adjusted within a range that allows the Sm and Fe sources and the La, W, and/or Co sources to substantially dissolve in the acidic solution. The acidic solution may be a sulfuric acid solution because of its solubility. The W source may be ammonium tungstate, and the Co source may be cobalt sulfate. These sources are each preferably prepared separately from the solution containing Sm and Fe and at a concentration within a range that allows it to substantially dissolve in water.