There are provided technologies for adsorbing a catalyst metal selectively to an anionic group such as a carboxyl group, thereby forming a metal film on a nonconductive resin selectively, including a palladium complex represented by the following formula (I): wherein L represents an alkylene group and R represents an amino group or a guanidyl group, or a structural isomer thereof, a processing solution for electroless plating catalyst application containing the complex as an active component, and a method for forming a metal plated film on a nonconductive resin, containing subjecting a nonconductive resin having a surface anionic group to a catalyst adsorbing treatment using the processing solution and then to a reduction treatment, electroless metal plating, and metal electroplating.