A polyarylene sulfide resin composition comprising a composition obtainable by a reaction of a polymer composition comprising(A) 100 parts by weight of a polyarylene sulfide resin,(B) 0.1 to 40 parts by weight of a monomer having one or more ethylenic unsaturated bonds and(C) 0 to 40 parts by weight of an unsaturated polyester. In the polyarylene sulfide resin composition of the present invention, a polymer produced by polymerization of the monomer or the monomer and unsaturated polyester, as compared with a resin composition wherein said polymer is simply blended, is in a state wherein it is uniformly mixed with the polyarylene sulfide resin and if necessary a filler. In other words, said polymer is uniformly dispersed in and mixed with the polyarylene sulfide resin to such a degree that the composition shows no phase separation even if it is passed through molding processes such as extrusion molding, injection molding, etc. carried out under normal conditions. Futher, the amount of said polymer added to the polyarylene sulfide resin is so proper that an excellent-performance resin composition to which an adhesive property of paint film (paintability) has been given, is obtained without a large reduction in the excellent properties of the polyarylene sulfide resin.