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 processor configured to detect one or more persons from image information obtained by capturing images covering an area around the item placement area; a part-of-interest detection processor configured to detect, for each person detected by the person detection processor, a part of interest set only in a part of an upper body of the person excluding hands and arms; a position measurement processor configured to measure a position of the part of interest detected by the part-of-interest detection processor; an item pick-up action determination processor configured to obtain a displacement of the part of interest based on the position of the part of interest obtained by the position measurement processor and to determine whether each person detected by the person detection processor performed an item pick-up action based on the displacement of the part of interest of the person; and an output information generation processor configured to generate output information representing a result of analysis based on a result of determination by the item pick-up action determination processor.