The aqueous resin composition comprises components (A) and (B), wherein (A) is a synthetic resin emulsion prepared by emulsion-polymerizing a radical-polymerizable unsaturated monomer using a surfactant having at least one polymerizable unsaturated bond, and (B) is a polyphosphate salt.To provide an aqueous flame retardant resin composition which is excellent in flame retardancy and storage stability, and is less likely to produce a fogging phenomenon.