There are provided a silver ink composition which is capable of forming metallic silver having sufficient electrical conductivity without carrying out a heat treatment at high temperatures; and a conductor and communication device which are obtained using this silver ink composition. Such a silver ink composition is characterized by being obtained by blending: a silver carboxylate having a group represented by a formula “—COOAg”; one or more nitrogen-containing compounds selected from the group consisting of amine compounds and quaternary ammonium salts of not more than 25 carbon atoms, ammonia, and ammonium salts obtained by reacting the above amine compounds or ammonia with an acid; and one or more reducing compounds selected from the group consisting of oxalic acid, hydrazine and compounds represented by a general formula (5) shown below (in the formula, R21 represents an alkyl group, alkoxy group or N,N-dialkylamino group of not more than 20 carbon atoms, a hydroxyl group or an amino group): or obtained by preparing a second mixture by supplying carbon dioxide to a first mixture formed by mixing a silver carboxylate having a group represented by a formula “—COOAg” and one or more nitrogen-containing compounds selected from the group consisting of amine compounds and quaternary ammonium salts of not more than 25 carbon atoms, ammonia, and ammonium salts obtained by reacting the amine compounds or ammonia with an acid; and further mixing one or more reducing compounds selected from the group consisting of oxalic acid, hydrazine and compounds represented by a general formula (5) shown below to the mixture: H—C(═O)—R21 (5).