Disclosed is a position management device and the like which allow for high precision calculation of the positional information on an object being monitored from an image taken by a monitoring camera.The position management device includes: a calculation unit that gives identification information on an object being monitored to the object being monitored cyclically imaged by an imaging device, and calculates positional information of the object being monitored from an image of the imaged object being monitored; a storage unit that associates the identification information of the object being monitored and an imaging time with the positional information, and stores these associated items; and a comparison unit that compares, with respect to the object being monitored, an absolute value of a difference between a value of the positional information as of a current time and a value of the positional information as of each of the imaging times one cycle and two cycles prior to the current time, as stored in the storage unit, with a predetermined reference value, and outputs the positional information as of the current time if the absolute value of the difference for at least one of the imaging times is less than the reference value.