A thermosetting resin composition using a transesterification reaction as a curing reaction, which has a good curability and can be used in various applications. A thermosetting resin composition comprising a polymer (A) composed of a monomer having a (meth) acrylic acid tertiary alkyl ester and a monomer having a hydroxyl group as a structural unit, and a transesterification catalyst (B) as an essential component, and being organic solvent-type or water-borne, wherein the polymer (A) has a glass transition temperature of 80° C. or lower.