PURPOSE: To enable exchange of vacuum meters while maintaining good vacuum state without adsorption of air on the inner wall of the main body of a vacuum device by constituting the device so as not to require changing of the inner state of the main body from reduced pressure state to atmospheric state.

CONSTITUTION: The vacuum device main body 1 and the vacuum meter 2 are shielded from each other with a first stop valve 3 provided on the connecting part. A second stop valve 5 is provided in the vacuum meter 2 side for an evacuation pump 4. Further, a third stop valve 7 is provided for a ventillation inlet 6. As a result, it is not necessary to change the inner state of reduced pressure in the vacuum device main body to atmospheric state, so that the vacuum meter can be exchanged while maintaining the good vacuum state without adsorption of air on the inner wall of the main body of the vacuum device.