1. A person behavior analysis device for performing analysis of item pick-up actions, which are actions of picking up an item placed in an item placement area, the device comprising: a person detection unit configured to detect a person(s) from image information obtained by capturing images covering an area around the item placement area; a part-of-interest detection unit configured to detect, for each person detected by the person detection unit, a part of interest set in a part of an upper body of the person excluding hands and arms; a position measurement unit configured to measure a position of the part of interest detected by the part-of-interest detection unit; an item pick-up action determination unit configured to obtain a displacement of the part of interest based on the position of the part of interest obtained by the position measurement unit and to determine whether each person detected by the person detection unit performed an item pick-up action based on the displacement of the part of interest of the person; and an output information generation unit configured to generate output information representing a result of analysis based on a result of determination by the item pick-up action determination unit.