A resinous composition for powder coating, comprising (A) an acrylic resin and (B) a hardener, the acrylic resin being composed of (a) t-butyl methacrylate and/or t-butyl acrylate, (b) an ethylenically unsaturated monomer having a reactive functional group and (c) other ethylenically unsaturated monomer(s) than the said (a) and (b) which is (are) non-reactive with the functional group of (b), the reactive functional group content being 0.0010-0.0046 mol/g of resin, the glass transition temperature being 30-110.degree. C. and the number average molecular weight being 1,000-20,000, and the hardener having in its molecule 2 or more functional groups which are reactive with the reactive functional group possessed by the acrylic resin.The powder coating based on the present resinous composition is useful for the coating of construction material, auto-mobile and the like and is excellent in low temperature curing properties, storage stability and can result an excellent film even when used a stored powder.