PROBLEM TO BE SOLVED: To discharge drain from a drain tank on the way of vacuum cooling operation of a vacuum cooling apparatus.SOLUTION: A vacuum cooling apparatus includes: a treatment tank 2 for storing an object to be cooled a vacuum generation device 1 connected to the treatment tank 2 by a vacuum piping 9 to suck gas in the treatment tank a heat exchanger 4 for cooling the gas sucked from the treatment tank 2 by the vacuum generation device 1 on the way and a drain tank 6 for storing drain generated in the heat exchanger. The vacuum cooling apparatus further includes: a drain tank shield valve 5 for shielding between the heat exchanger 4 and the drain tank 6 and a vacuum piping shield valve 12 for shielding between the treatment tank 2 and the heat exchanger 4, and is configured so that when discharging drain during vacuum cooling operation, the drain tank shield valve 5 is closed to discharge the drain, and after discharging the drain, the treatment tank 2 is separated from a vacuum path by closing the vacuum piping shield valve 12, pressure in the drain tank is reduced by opening the drain tank shield valve 5 and the vacuum piping shield valve 12 is opened after reducing pressure in the drain tank.
