An aqueous silver-containing solution comprising nano-sized silver particles wherein silver (Ag) particles having a particle diameter of 1 to 20 nm have a concentration of 200 to 100,000 ppm, the pH of the solution is maintained in a range of 6 to 8.5, and based on the weight of the silver-containing solution, an amount of a stabilizer as an impurity is in a range of 0.5 to 1.5% by weight, an amount of anions of a silver salt as another impurity is 1.0% by weight or less and the total amount of the stabilizer and anions of the silver salt is 2.0% by weight or less; an antibacterial resin composition comprising 100 parts by weight of an acrylic, urethane, epoxy or ester resin, 0.05 to 5 parts by weight of a curing agent and a silver-containing solution in an amount such that a concentration of silver is in a range of 5 to 100 ppm, relative to the resin composition; and an antibacterial resin-coated steel plate having a dry film thickness of not more than 5 .mu.m which is formed by coating of the aqueous antibacterial resin composition. Steel plates coated with the antibacterial resin composition exhibit superior antibacterial properties, corrosion resistance, conductivity and adhesion.