To obtain a powder coating material which is low in cost and forms a coating film excellent in external appearance and weatherability by compounding a specific vinyl copolymer with an aliph. dibasic acid.

11-30 pts.wt. vinyl monomer having a silyl group of the formula, 1-30 pts.wt. glycidylated vinyl monomer, and 88-40 pts.wt. other copolymerizable vinyl monomer are copolymerized in the presence of a free-radical initiator to give a vinyl copolymer which comprises 95-50 pts.wt. vinyl copolymer having a glass transition temp. of 40-100°C and 5-50 pts.wt. vinyl copolymer having a glass transition temp. of -20 to 39°C, contains silyl groups of the formula as the main crosslinking groups, and has a number average mol.wt. of 2,000-20,000. 100 pts.wt. this vinyl copolymer is compounded with 1-30 pts.wt aliph. dibasic acid. In the formula, R1 is 1-10C alkyl, 6-10C aryl, or 7-10C aralkyl; X is H, halogen, hydroxy, alkoxy, phenoxy, thioalkoxy, acyloxy, aminoxy, ketoximate, amino, or the like; and a is 0-2.