To provide a gypsum-based investment material composition for casting and a method for manufacturing the same, the investment material composition being useful as a flash-heating-type gypsum-based investment material for making it possible to provide a product in which exposure time is reduced, such reduced exposure time not having been realized in the conventional product. A gypsum-based investment material composition for casting and a method for manufacturing the same, the investment material composition being a gypsum-based powdery investment material composition for casting, for use as a flash-heating-type investment material to which a malaxation liquid is added, the mixture is cured after malaxation, and the cured product is placed in a high-temperature furnace, wherein the gypsum-based investment material composition for casting has calcined gypsum, quartz, and cristobalite as main components thereof, the gypsum-based investment material composition for casting includes a powder or a liquid moisture-retaining component having a low water content and any one co-pulverized material selected from a co-pulverized material of calcined gypsum and quartz, a co-pulverized material of calcined gypsum and cristobalite, or a co-pulverized material of calcined gypsum, quartz, and cristobalite, and the gypsum-based investment material composition for casting has an average particle diameter of 30 µm or less.
