Abstract: An exposure apparatus equipped with a substrate supervisory device is contained in an air-conditioned chamber with a front door. The device has a library for storing a plurality of reticle cases with respective reticles therein, a bar code reader for reading respective bar codes of the reticle cases and shifting means for shifting the bar code reader for the reading. When an operator stores the cases in the library by opening the door of the chamber, the bar code reader is retreated to a predetermined position and the shifting means will not be activated for the operator's safety.