A heat-curable resinous coating composition comprising as a binder component(A) 5 to 90% by weight of a hydroxyl-containing resin selected from hydroxyl-containing acrylic resins and hydroxyl-containing polyester resins,(B) 5 to 50% by weight of an amino resin, and(C) 1 to 90% by weight of a crosslinkable resin selected from (C-a) polyfunctional resins having a number average molecular weight of at least 1000 and containing at least two carboxyl groups and at least two epoxy groups on an average per molecule and (C-b) polyorganosiloxanes having a number average molecular weight of at least 500 and containing at least two silanol groups on an average per molecule and if required, further containing an epoxy group.