To provide a vacuum device by which the exhausting performance of the vacuum device can be kept in a good condition regardless of the temperature change of the sealing water to be supplied to a sealing water type vacuum pump.

In a vacuum device wherein an ejector 8 is mounted on a path 6 connecting a vacuum container 2 and a sealing water type vacuum pump 1, and the ejector 8 is started when the pressure at an inlet side of the ejector 8 is agreed with a set pressure value, a temperature measuring means 12 for measuring the temperature of the sealing water is mounted on a supply path 3 for supplying the sealing water to the sealing water type vacuum pump 1, and a controlling means 14 changes the set pressure value at the inlet side of the ejector 8 corresponding to the temperature of the sealing water.