PURPOSE: To easily produce a box having pressure-resistant and explosion proof construction made of aluminum die-cast product by spraying molten aluminum into a die to prepare a box of aluminum casting and subjecting this casting to artificial age hardening treatment.

CONSTITUTION: An aluminum casting of box is prepared by spraying molten aluminum into a die, and this aluminum casting is hardened at about 400-520°C, preferably about 420-500°C, and tempered at about 160-200°C to undergo artificial age hardening treatment. By this method, the box made of aluminum die-cast product having ≥ about 25kg/mm2 tensile strength and pressure-resistant and explosion-proof construction can be obtained.