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.本發明提供一種鑄造用包埋材組成物,其係於使用消失溫度或消失行為與習知之蠟模型不同之樹脂模型,且藉由處理效率優異之「急速加熱」進行鑄造之情形時,可進行良好之鑄造。本發明係一種鑄造用包埋材組成物及使用其之鑄件之鑄造方法,該鑄造用包埋材組成物之特徵在於:不使用熱膨脹性耐火材料作為主成分,而將結合材料、及平均粒徑為5~20μm之非熱膨脹性耐火材料作為主成分而成,於將該主成分之合計設為100質量份之情形時,結合材料之含量為25~40質量份,且非熱膨脹性耐火材料之含量為60~75質量份。
