To prepare a heat-resistant synthetic paper sheet which is excellent in heat resistance, printability and surface smoothness and is suitably used as a substrate, or the like, of a heat-resistant label, a heat-resistant insulating material, and the like.

The heat-resistant synthetic paper sheet comprises a resin having a glass transition temperature of ≥130°C and has a porosity of 20-98 vol.%. The synthetic paper sheet is manufactured by placing a resin solution comprising the resin having a glass transition temperature of ≥130°C between at least two carriers, processing the resin solution into a thin film by passing it through a roll, a slit or press equipment, introducing the thin film into a solidifying bath and releasing the carriers to solidify the thin film in the solidifying bath.