Resin compositions for powdery coatings which contain the components (A), (B) and (C) as specified below: (A) a carboxyl-containing resin having a number-average molecular weight of 1,000 to 20,000, an acid value of 5 to 200 and a glass transition temperature of 30 to 120 °C; (B) a poly-β-methylglycidyl compound carrying at least two structures represented by formula (1) per molecule; and (C) a steric-hindered amine as a heat yellowing inhibitor.