A system with an intelligent shelf (100) has product display shelves (110 to 130) displaying products having RFID tags R. The system includes antennas (112a to 112c) each having unique antenna numbers and detecting a tag serial number from an RFID tag on a product, human body sensors S disposed on each end of the product display shelf 120, a tag-product ID registration table storing the tag serial numbers of the RFID tags and the product IDs of the products and a control computer (200) detecting that a particular product is picked up from and/or returned to a particular product display shelf by combining the input tag serial number and the antenna number of the antenna detecting the tag serial number and analyzing which direction the detected human body has moved based on the difference of the detection times of the human body sensors.