To provide a method for manufacturing a cast product using a chiller, which method can surely exert the cooling effect of the chiller irrespective of the size and shape of the cast product.

In this method for manufacturing the cast product, a chiller having a thermal conductivity of 0.06 cal/(cm×s×°C) or more at an ordinary temperature is buried in a casting mold so as to come into direct contact with molten metal or so as to come in the proximity to the molten metal. Furthermore, heat conductive material blocks having a thermal conductivity of 0.3 to 2 times as large as that of the chiller at an ordinary temperature are connected to both ends of the chiller so as not to come into contact with the molten metal.