To provide a resin composition that forms coating films exhibiting excellent adhesion to various moldings etc. and that is excellent in storage stability at low temperature.

The resin composition is provided by mixing a photopolymerization initiator (d) in a resin solution (a) containing a modified product of a propylene-1-butene copolymer (A) in organic solvent. The propylene-1-butene copolymer (A) includes 50-95 mol% of propylene units and 5-50 mol% of 1-butene units and has a molecular weight distribution in the range of 1-3 as measured by GPC and a limiting viscosity of 0.1-12 dl/g. The modified product of the propylene-1-butene copolymer (A) is obtained by polymerizing a particular copolymerizable monomer (C) in the presence of a propylene-1-butene copolymer (A) in organic solvent at a weight ratio of (A)/(C)=1/9 to 9/1 to provide a resin mixture, followed by further carrying out polymerization reaction by generating radical.