PURPOSE: To obtain magnetic powder having high saturation magnetization, high coercive force and excellent corrosion resistance by forming an aluminum compound layer and a magnetic metallic layer mainly comprising nickel and/or cobalt onto the surfaces of metallic magnetic powder mainly comprising iron.

CONSTITUTION: An aluminum compound and a ferromagnetic metal such as metallic nickel and/or cobalt or an alloy are shaped onto the surfaces of metallic ferromagnetic powder. Purple oxide as a raw material is treated by using aluminum sulfate and carbon dioxide in a sodium hydroxide aqueous solution as a method in which the aluminum compound is formed. It is preferable that the quantity of the aluminum compound shaped is brought to 2W15wt.%. A means in which the ferromagnetic metallic alloy of metallic nickel and/or cobalt and the like is formed is not limited particularly. A general technique for forming a metallic layer such as a method, in which electroless plating is conducted directly onto the surfaces of metallic ferromagnetic powder, etc. can be adopted arbitrarily. An extremely uniform magnetic metallic alloy layer, which does not damage the shapes of iron oxide magnetic powder, can be shaped onto the surfaces of the powder by a reaction such as a photocatalytic reaction.