A commodity monitoring device includes a visitor number acquirer that acquires the number of visitors, a purchasing customer number acquirer that acquires the number of purchasing customers who purchase a commodity, a statistical information generator that generates statistical information, based on the number of visitors and the number of purchasing customers, a commodity detector that detects commodity, based on a captured image of a display area, a sales opportunity loss analyzer that analyzes a cause of the sales opportunity loss from a commodity detection result, and a display screen generator that generates a monitoring screen in which a display image representing the cause of the sales opportunity loss is superimposed on the image of the display area.