The present invention relates to a plating solution useful for forming embedded interconnects by embedding a conductive material in fine recesses for interconnects provided in the surface of a substrate, such as a semiconductor substrate, or for forming a protective layer for protecting the surface of embedded interconnects, a semiconductor device manufactured by using the plating solution and a method for manufacturing the semiconductor device. The plating solution contains copper ions, metal ions of a metal, and the metal is capable of forming with copper a copper alloy in which the metal does not form a solid solution with copper, a complexing agent, and a reducing agent free from alkali metal.