The present invention provides an anticorrosion coating method for a galvanized steel structure, the method comprising applying an undercoating composition (I) to a cured thickness of 10 to 200 mum to a surface of a galvanized steel structure, and then applying thereto an overcoating composition (II) to a cured thickness of 100 to 1,500 mum; the undercoating composition (I) comprising an epoxy resin (A) having two or more epoxy groups per molecule, a specific amount of a resin (B) such as a urethane-modified epoxy resin, and an amine-based curing agent (C); the undercoating composition (I) having a shrinkage stress of 20 kg/cm2 or less when it is in the form of a 50 mum-thick cured coating film; and the overcoating composition (II) comprising an epoxy resin (D) having two or more epoxy groups per molecule, a specific amount of a flaky pigment (E), and an amine-based curing agent (F).