An apparatus and method for preventing an anomaly of an application program are provided. More particularly, an apparatus and method for preventing an anomaly of an application program that detect and stop an anomaly on the basis of a behavior profile for an application program are provided. The apparatus includes a behavior monitor that detects behavior of an application program in operation, an anomaly detector that determines whether the detected behavior of the application program is an anomaly on the basis of a behavior profile of the application program in operation, and an anomaly stopper that stops the behavior of the application program determined as an anomaly by the anomaly detector. Possible application program behavior is stored according to its purpose in a behavior profile and an anomaly is detected and stopped on the basis of the behavior profile, thereby decreasing a false-positive rate of anomaly detection and simultaneously solving a problem of a conventional security programs being incapable of defending against attacks using the authority of a program trusted by a user.