PURPOSE: To obtain the titled die cast Al product by keeping a molten Al-Si alloy contg. a specified amount of Si at a temp. below the liquidus line to crystallize proeutectic Si and by die casting the molten alloy contg. the proeutectic Si.

CONSTITUTION: A molten Al-Si alloy contg. 20W35% Si is kept at a temp. ≥20°C, especially ≥30°C below the liquidus line to crystallize proeutectic Si, and the molten alloy contg. the proeutectic Si is die cast by an ordinary method to obtain a die cast Al product with high damping capacity and superior mechanical strength. When the Si content of the molten alloy is <20%, high damping capacity is not provided, and >35% Si content deteriorates the machinability.