A metallic composite in which a conjugated compound having a molecular weight of 200 or more is adsorbed to a metallic nanostructure having an aspect ratio of 1.5 or more, for example, a metallic composite in which a compound having a group represented by the formula (I) or a repeating unit represented by the formula (II) or both of them is adsorbed to a metallic nanostructure having an aspect ratio of 1.5 or more, is useful for electronic devices such as a light-emitting device, a solar cell and an organic transistor.