PURPOSE: To shorten cycle time of die casting machine to raise productivity, to improve and clean working environment and to keep health of workers by adopting an outer cooling system as cooling system for metallic die to carry out cooling uniform by simultaneously direct atomizing very large quantity of water on the surface of metallic die in a very short time and using powder release agent instead of water-soluble agent.

CONSTITUTION: A device is provided with a water tank 2 in which cooling water for metallic die is stored, an air tank 19 in which high pressure air for atomizing cooling water is stored and a pressure container 14 by which the cooling water led from the water tank 2 and stored is simultaneously discharged to the outside of container utilizing high pressure air led from the air tank 19 in other route and the discharged water is supplied to a spray head 33.