PURPOSE: To obtain a resin composition containing a specific (metha)acrylate compound, a half ester compound and a photopolymerization initiator, of which cured material is excellent in acid resistance, adhering properties, weather resistance,etc., useful for an automobile coating material trifunctional, etc.

CONSTITUTION: This resin composition comprises (A) a trifunctional (metha) acrylate compound, such as trimethylolpropanetri(metha)acrylate, dipentaerythritolpenta(metha)acrylate, etc., (B) a half ester compound such as an equimolar reaction product of succinic anhydride with 2-hydroxyethyl(metha)acrylate, an equimolar-reaction product of hexahydrophthalic anhydride with 2-hydroxyethyl(metha)acrylate, etc., and (C) a photopolymerization initiator such as benzophenone, l-hydroxycyclohexylphenylketone, etc.