Electroless plating liquid and semiconductor device

The present invention relates to an electroless-plating liquid useful for forming a protective film for selectively protecting surface of exposed interconnects of a semiconductor device which has an embedded interconnect structure formed by an electric conductor, such as copper or silver, embedded in fine recesses for interconnects formed in a surface of a semiconductor substrate, and also to a semiconductor device in which surfaces of exposed interconnects are selectively protected with a protective film. The electroless-plating liquid contains cobalt ions, a complexing agent and a reducing agent containing no alkali metal.