A product management system is disclosed. The product management system comprises a product detection device disposed on a product display rack and configured to detect presence/absence of a product on the product display rack, a wireless communication device disposed on the product display rack and configured to wirelessly transmit information about the presence/absence of the product detected by the product detection device, a relay device to relay communications between the wireless communication device and a network, a product management device to store and display the information transmitted from the wireless communication device via the relay device and the network, and a terminal device capable of wireless communications with the wireless communication device and configured to travel with a shopper.