A substrate processing method is useful for forming, by electroless plating, a protective film, such as a magnetic film, which covers exposed surfaces of embedded interconnects composed of an interconnect material, such as copper or silver, embedded in fine interconnect recesses provided in a surface of a substrate. The substrate processing method includes bringing a surface of a substrate into contact with a processing solution whose temperature is adjusted to not more than 15° C., thereby activating the surface, and bringing the activated surface of the substrate into contact with a plating solution, thereby forming a metal film on the surface.