A wireless power transmitter that transmits power to a wireless power receiver, the wireless power transmitter including a wireless communication unit configured to communicate with the wireless power receiver; and a controller, wherein the wireless communication unit receives, from the wireless power receiver, a first foreign object status packet and a second foreign object status packet and transmits, to the wireless power receiver, a foreign object detection indicator indicating whether a foreign object is present in a charging area of the wireless power transmitter, wherein the controller is configured to generate the foreign object detection indicator, wherein the first foreign object status packet includes a first reference value and mode information, wherein the second foreign object status packet includes a second reference value and mode information, wherein the mode information of the first foreign object status packet indicates whether the first reference value is a reference quality factor or a reference peak frequency of the wireless power receiver, and wherein the mode information of the second foreign object status packet indicates whether the second reference value is the reference quality factor or the reference peak frequency of the wireless power receiver.