Mg-1∼20mass%Li-1∼5mass%Al alloys were cast into Tatur mold. When Al was added to Mg-Li alloys, AlLi phase was formed with the addition of 3mass% or more Al. Exterior shrinkage decreased as the amount of Al added increased. The addition of Al was effective in reducing interior shrinkage for Mg-8∼20mass%Li alloys but not for Mg-1∼5mass%Li alloys. When 1∼5 mass%Al was added to Mg-1∼14mass%Li alloys, porosities increased as the amount of Al added increased. For Mg-16∼20mass%Li alloys, porosities decreased by the addition of Al.