To miniaturize and lighten an evacuation system in technology effectively applicable to miniaturize and lighten an evacuation system of a mass spectrograph.

A structure of the evacuation device A can be miniaturized and lightened as compared with a conventional one by using a turbo molecular pump 20 for a main pump connected to a vacuum tank and connecting a diaphragm pump 30 as an auxiliary pump to the turbo molecular pump 20. The evacuation device A is used for an evacuation system of a coaxial reflection type flight analysis tube 40. Cooling material is provided on a heat generation part of the diaphragm pump 30 to effectively cool heat generation at a time of evacuation system operation. A mass spectrograph B can be lightened and miniaturized as compared with one using a scroll pump 60 as an auxiliary pump.