To obtain a chiller for casting a light alloy, in which the durability is obtained with light weight and high hardness of the chiller, and heat expansion rate is small and heat-conductivity is high and the cooling performance is excellent.

In molten aluminum alloy as the raw material, having 20 wt.% silicon, silicon carbide (SiC) ceramic powder having 10-15m grain diameter is mixed portionwise into the molten alloy at 30 wt.% and the ceramic powder is uniformly dispersed into the molten alloy. The molten aluminum alloy 14 is poured into an upper sand mold 15 and a lower sand mold 16 to cast the chiller 17 in the sand mold.