A monitoring device and method, of a vacuum-system device having a vacuum portion, which can collectively perform the maintenance control of the device or counter measures to overcome drawbacks by providing a monitoring method equivalent to monitoring in real time and simultaneously based on data from respective types of sensors of the vacuum system. By visualizing the state of a driving system in a vacuum, a vacuum valve, a vacuum state and a state of an electro-optic system on a screen, the device state in a vacuum may be grasped. Further, it is possible to perform the time measuring and the comparison of data with the reference data by setting up timing charts with respect to the ON/OFF timing of various sensors, Open/Close timing and vacuum state.