Disclosed is a heat-curable powder coating composition that allows the formation of a coating film having outstanding long-term corrosion resistance, as well as outstanding chipping resistance, flexibility, and adhesion.The disclosed heat-curable powder coating composition is characterized by a resin having crosslinkable functional groups that are solid at room temperature (A), a curing agent capable of reacting with said crosslinkable functional groups (B), a fibrous filler (C), and heat-expandable resin particles (D).