A commodity management device includes a camera interface circuit connectable to a camera to capture an image of one of commodities arranged in a row along a first direction from a back plate to a front of the shelf. The device includes a sensor interface circuit connectable to a sensor measuring a distance to the commodities in the row. A processor is configured to detect a change in the distance measured by the sensor, identify the commodities based on the image, then acquire a thickness of each commodity in the row, and calculate the number of the commodities removed from the shelf based on the distance change and the thickness of the commodities.