A method for manufacturing an Al—Si—Mg aluminum alloy casting material is provided. The method for manufacturing an Al—Si—Mg aluminum alloy casting material includes performing heat treatment on an Al—Si—Mg aluminum alloy casting material containing 5 mass % or larger and 10 mass % or smaller of Si, 0.2 mass % or larger and 1.0 mass % or smaller of Mg, 0.03 mass % or larger and 0.5 mass % or smaller of Sb, and 0.0004 mass % or larger and 0.0026 mass % or smaller of Be, and a remainder having an alloy composition including Al and unavoidable impurities.