A surface treatment agent from which a surface layer having an excellent friction resistance can be formed, an article including such a surface layer, and a method for manufacturing such an article are provided. A surface treatment agent according to the present invention contains a fluorine-containing ether compound including a fluoro-polyether chain and a reactive silyl group; a first metallic compound containing a first metallic element; and a second metallic compound containing a second metallic element different from the first metallic element.