An object of the present invention is to provide a method for forming a coating film that is capable of forming a coating film having excellent smoothness, distinctness of image and luster using an aqueous coating composition. The present invention provides a method for forming a coating film comprising: Step (1): forming an uncured coating film by applying to a substrate an aqueous coating composition that contains a copolymer of monomer components comprising one or more N-substituted (meth)acrylamide compounds, the copolymer being a graft copolymer comprising (A) a main chain having a lower critical solution temperature T1 in water within the range of 30 to 95° C., and (B) at least one hydrophobic side chain; Step (2): preheating the uncured coating film formed in Step (1) under heating conditions such that a preheating temperature T2 falls within the range of 60 to 100° C., and the preheating temperature T2 and the lower critical solution temperature T1 have a relationship represented by the formula T2−T1=−30 to 30° C.; and Step (3): curing the uncured coating film formed in Step (2) by heating.