an abnormality detection apparatus for detecting an event where a monitored object in a room has lapsed into an abnormal state . the apparatus includes an image pickup system for picking up an image of a scene in the room , and feature - quantity extraction devices for extracting an image feature quantity from the image picked up by the image pickup devices . the apparatus also includes judgment devices for determining whether the monitored object in the room has lapsed into the abnormal state or not based on the time - variations of the image feature quantity extracted by the feature - quantity extraction devices , and outputting an alarm that responds to the determination of the occurrence of the abnormal state .