To provide an aluminum alloy for a cast joint member of an automotive space frame, which is sand-cast from the aluminum alloy, and to provide a method for manufacturing the cast joint member using it.

The aluminum alloy for the cast joint member of the automotive space frame includes aluminum as a main material, 0.4-0.5 wt.% copper (Cu), 2.5-3.0 wt.% silicon (Si), 0.1 wt.% or less magnesium (Mg), 0.1 wt.% or less iron (Fe) and 0.20 wt.% or less titanium (Ti). The method for manufacturing the cast joint member using the alloy comprises: casting the aluminum alloy; solution-treating it; and heat-treating it at 150 to 160°C for 4 to 5 hours.