Provided are a metal nanoparticle composite which exhibits excellent stability over time and retention stability and is useful as a raw material for a metal nanoparticle-dispersed film, a method for producing the composite, a metal nanoparticle dispersion liquid, a composition for forming a metal nanoparticle-dispersed film, and a metal nanoparticle-dispersed film. Disclosed is a metal nanoparticle composite comprising (A) a star-shaped polymer having a central core and arms bonded to the central core, the arms comprising a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2); and (B) metal nanoparticles supported thereon: wherein in the formula (1), R1 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; and in the formula (2), R2 represents a methyl group or an ethyl group; and k represents an integer from 1 to 10.