Provided is an aqueous coating composition capable of forming a coating film having superior metallic coating film appearance and coating film properties and reducing the amount of an organic solvent to be used. Also provided is a method for forming a metallic coating film using such an aqueous coating composition. Provided is an aqueous coating composition comprising a coating film-forming resin, a curing agent, a scaly pigment, an inorganic viscosity agent, a hydrophobic associative viscosity agent, and a dispersant, wherein the composition contains the inorganic viscosity agent in an amount of 1 to 7 parts by mass based on 100 parts by mass of the total resin solid content of the coating film-forming resin and the curing agent, and the composition contains the hydrophobic associative viscosity agent in an amount of 1 to 15 parts by mass based on 100 parts by mass of the total resin solid content of the coating film-forming resin and the curing agent.