PURPOSE: To prevent a pump from becoming a source of vibrations during operation by a method wherein a turbo-molecular pump is set on a floor and the connection of a device for vacuum exhaustion with the turbo-molecular pump is constructed in a vibration-proof manner.

CONSTITUTION: A turbo-molecular pump 9 is set on a floor 10 through the intermediary of an absorbing body 17 which absorbs high-frequency vibrations, while the main body 8 of a scanning-type electron microscope is connected with the air- suction side of the turbo-molecular pump 9 through the intermediary of a valve 15 and a main-exhaust-pipe bellows 16 having an elastic structure. By this way, the high-frequency vibrtions at the starting time of the pump 9 are absorbed by the absorbing body 17, while the low-frequency vibrations are absorbed by the bellows 16 and by the elastic exhaust pipe 20. Therefore, the effect of the vibrations of the pump 9 upon the main body 8 is very little.