The object of the present invention is to provide an embedding material composition for casting that makes it possible to conduct a favorable casting in the case where casting is conducted using a resin pattern that is different from a conventional wax pattern in disappearance temperature and disappearance behaviors through “rapid heating” excellent in treatment efficiency. The present invention relates to an embedding material composition for casting not using a heat-expandable refractory material as a main component, comprising: a binder; and a non-heat-expandable refractory material having an average particle diameter of 5 to 20 μm as main components, in which a content of the binder is 25 to 40 parts by mass and a content of the non-heat-expandable refractory material is 60 to 75 parts by mass in the case where the total amount of the main components is 100 parts by mass, and the present invention also relates to a casting process using the embedding material composition for casting.