Catalyst-imparting treatment solution and electroless plating method

The present invention provides a catalyst-imparting treatment solution and an electroless plating method that can form a protective film of a phosphorus-containing alloy to protect the surface of copper inter-connects of an electronic device without forming voids in the copper inter-connects. The catalyst-imparting treatment solution, for use in a catalyst-imparting pretreatment before carrying out electroless plating of at least part of an electronic device having an embedded copper-interconnect structure using a hypophosphite as a reducing agent, includes at least one complex compound of a noble metal of Group IB or Group VIII of the Periodic Table.