A mixed gas containing a precursor gas, an additive gas and a carrier gas is supplied to a preform stored in an electric furnace, and silicon carbide is deposited by chemical vapor deposition or chemical vapor phase impregnation to form a film. The preform includes multiple fiber bundles, and the fiber bundles include multiple fibers. This heat-resistant composite material includes a ceramic fiber preform impregnated with silicon carbide, and producing the composite material involves a step in which silicon carbide is deposited between the fibers to integrate the fibers which configure the fiber bundles, and a step in which silicon carbide is deposited between the fiber bundles to integrate the fiber bundles. Hereby, uniformity of embedding and growth rate of the silicon carbide film are both attained.