The present invention relates to a foreign substance detection method, and an apparatus and a system therefor. A foreign substance detection method in a wireless power transmitter, according to an embodiment of the present invention, may comprise the steps of: if an object placed in a charging area is detected, searching for a current peak frequency with a maximum quality factor value in an available frequency band; receiving, from a wireless power receiver, a foreign substance detection state packet including a reference peak frequency; determining a foreign substance detection reference frequency on the basis of the reference peak frequency; and determining whether or not a foreign substance is present by comparing the current peak frequency with the foreign substance detection reference frequency. Therefore, the present invention has an advantage of being capable of detecting a foreign substance more effectively and accurately.