To prevent abnormal vibration from adversely affecting an exposing device on a mount by outputting a stop signal from a stop control means based on the output of a vibration detecting means and stopping the operation of the mount according to this stop signal.

The vibration of an exposing device main body 1 is detected by an acceleration sensor 3a and its output is inputted to a stop control part 7. When an output from the acceleration sensor 3a exceeds a fixed value because of the abnormal vibration of the exposing device main body 1, the stop control part 7 outputs a stop signal to an air pressure shut-off part 6. Upon receiving this stop signal, a solenoid valve makes a solenoid inactive and closes a duct line. At this time, the flow-in or the flow-out of air for an active mount 2 is stopped and then the operation of the active mount 2 is stopped.