To safely obtain a magnesium molded product with an existing plastic molding machine using molten plastic as a molding auxiliary material under the condition that the risk of explosion and ignition in the molding of molten magnesium is eliminated.

A preworked magnesium plate is inserted in a mold and the mold temperature and resin temperature are controlled below the ignition temperature of magnesium so as to perform an ordinary magnesium molding under the utilization of the properties of the magnesium plate softened below its ignition temperature in order to obtain the magnesium-covered molded product.