Japanese Patent Laying-Open No. 56-120771 (PTL 3), Japanese Patent Laying-Open No. 01-311176 (PTL 4), and Japanese Patent Laying-Open No. 06-032994 (PTL 5) disclose methods for forming a composite layer made of a metal oxide such as iron oxide or titanium oxide and carbon, a metal, a metal oxide or the like on the surface of a metallic pigment by a gas phase method.