An antibacterial agent of the present invention contains a metal-containing compound containing a metal other than aluminum, and a phosphorus-adsorbing material. A method of using an antibacterial agent of the present invention is a method for improving an antibacterial property of a metal-containing compound containing a metal other than aluminum, wherein the metal-containing compound and a phosphorus-adsorbing compound are used in combination. Thus, the present invention provides an antibacterial agent, and a method of using an antibacterial agent, wherein an antibacterial property of a metal-containing compound containing a metal other than aluminum, particularly a silver-containing compound, is improved significantly.
