Fault analysis, including accurate fault detection and careful fault avoidance, is very important for the stable and safe operation of a process. It is, however, difficult to rationally analyze faults occurring in a process using a rational process model. Since the behavior of a batch process is characterized by an event-driven state transition mechanism, a batch process is regarded as a discrete event system. The Petri net is a promising modeling tool for studies of discrete event systems. This paper presents a method of detecting faults and constructing fault avoidance controllers for batch processes with uncontrollable events and unobservable statuses based on Petri net analysis techniques and control schemes.