To detect the quantity of goods using a simple configuration. [Solution] The item detection device comprises a storage section in which fluid is stored, a placement section placed on the storage section on which an item is placed, a flow section communicating with the storage section, on which the fluid moves from the storage section when an item is placed on the placement section, and an RFID medium having an IC
chip and an antenna connected to the IC
chip, and placed at a predetermined position in the flow section, wherein the fluid moving in the flow section changes the state of radio
waves transmitted via the antenna according to the amount of items.