1. A behavior analysis device comprising: an object extraction portion that processes a frame image of an imaging area being imaged by an imaging device and extracts an object being imaged; a position detection portion that detects a position in the imaging area, for each object extracted by the object extraction portion; a posture estimation portion that estimates an posture of the object, for each object extracted by the object extraction portion; and a behavior determination portion that determines a behavior of the object, for each object extracted by the object extraction portion, based on the position in the imaging area that is detected by the position detection portion and the posture estimated by the posture estimation portion.