To provide an intrusion monitoring device in which transfer control to a warning mode is realized in an intrusion monitoring system which is safe and has high convenience.

An intrusion monitoring device, in which at least a warning mode and a warning release mode are provided as a security mode, and an intruding object to a monitoring area is monitored, includes: object detection means for detecting an intrusion object appearing in the monitoring area and a position of the intrusion object; abnormality discrimination means for performing abnormality discrimination on the basis of a result of the detection of the intrusion object in a warning mode; and mode control means, which is means for performing transition setting from a warning release mode to a warning mode in accordance with a changeover instruction, for determining whether or not the transition setting to the warning mode is allowed on the basis of a position of the intrusion object in the monitoring area when the intrusion object is detected. Thereby, transition setting to the warning mode can be performed in view of an influence to intrusion monitoring in accordance with a position of the intrusion object, so that utilization of high convenience is realized.