Abstract: Provided are a heat-curable resin composition that yields a molded article having excellent dimensional accuracy and mechanical property even when high-temperature molding is carried out, a production method of article and a molded article thereof, a cured article, a molded article, and a separator for a fuel cell. A heat-curable resin composition in an embodiment of the present invention comprises: (A) a binder in an amount of 100 parts by mass comprising 50 mass % or more of a polymer comprising 60 mol % or more monomer units having a carbon-carbon double bond in a side chain; (B) a carbon material in an amount of 150 to 1,000 parts by mass; (C) a curing initiator in an amount of 1 to 10 parts by mass; and (D) a curing retarder in an amount of 0.1 to 2 parts by mass.