An evaporative pattern casting process includes forming a mold by burying a pattern made of resin foam in casting sand, pouring molten metal into the mold, and evaporating the pattern with the molten metal and thereby casting a product. In the evaporative pattern casting process, casting time during founding is set according to a modulus (pattern volume÷pattern surface area) of the pattern. Accordingly, the casting time in the evaporative pattern casting process is accurately set with high precision.