PROBLEM TO BE SOLVED: To shorten a cooling operation time and to prevent occurence of bumping by starting slow cooling at a proper timing even when temperature unevenness is found on a cooled object.SOLUTION: In the vacuum cooing device including a cooling tank 2 receiving the cooled object 7, a temperature measuring device 11 for measuring a temperature of the cooled object in the cooling tank, a pressure measuring device 5 for measuring a pressure in the cooling tank, and a vacuum generating device 1 for discharging the air in the cooling tank, and executing a slow cooling operation to lower a pressure reduction speed in a cooling operation, the slow cooling operation is not executed, but pressure reduction in the cooling tank is executed until earlier one of the time when the pressure in the cooling tank reaches a set pressure determined on the basis of a saturated vapor pressure corresponding to a temperature of the cooled object in starting the cooling operation, and the time when the temperature of the cooled object changes by a prescribed temperature from the temperature in starting the cooling operation, and the slow cooling operation is started when the pressure in the cooling tank reaches the set pressure or the temperature of the cooled object changes by the prescribed temperature or more from the start of cooling.
