An active energy ray-curable resin composition which is excellently adhesive to a base material, an undercoat agent which is for a metal thin film and includes the resin composition, and a formed material obtained using the undercoat agent for a metal thin film are provided. The active energy ray-curable resin composition includes, as essential components, an alkyd resin (A), an unsaturated bond-containing polymerizable compound (B), a phenolic compound (C) represented by the following structural formula (1) wherein R1 is a hydrogen atom or a hydrocarbon group), and a photopolymerization initiator (D) having a structural moiety represented by the following structural formula (2) wherein R3's are any of an aliphatic hydrocarbon group, an aryl group, an aralkyl group, an alkoxy group, a hydroxyl group and an amino group, wherein two or more of the R3's may form a ring structure.