To provide a magnetplumbite-type ferrite material powder having fine particles, sharp particle distribution and uniform composition, at a low manufacturing cost.

The chloride-dissolved mixture solution containing a chloride of iron, a chloride of strontium and at least one chloride of metal selected from lanthanum, cobalt, manganese and nickel is sprayed into a roasting furnace 10 in the heated atmosphere, and the chloride-dissolved mixture solution is changed to the magnetoplumbite-type ferrite material powder 16. In this process, an inflammable gas and/or oxygen gas are blown into or an inflammable solvent is sprayed into the area 17 where the above chloride-dissolved solution is changed into the magnetoplumbite-type ferrite material powder.