A cold formation method of composite silver nanoparticles has been established. Thus, provided are composite silver nanoparticles comprising a silver core, which is made up of aggregated silver atoms and has an average particle diameter of from 1 to 20 nm, and an organic coating layer formed thereon which comprises at least one member selected from an alcohol molecule derivative having 1 to 12 carbon atoms, an alcohol molecule residue or an alcohol molecule; a composite silver nanopaste which contains at least the composite silver nanoparticles and a solvent and/or a viscosity grant agent added thereto; a method of producing the same; an apparatus for producing the same; a method of bonding the same; and a method of patterning the same. The method of producing the composite silver nanoparticles comprising mixing silver salt microparticles with an alcohol solvent in excess to prepare an excess alcoholic solution, reacting the solution in a reaction chamber for a predetermined period of time at a predetermined temperature, and thus forming silver cores from the silver salt at a low temperature by the reducing effect of the alcohol and also forming an organic coating layer derived from the above-described alcohol around the silver cores.