Disclosed is a method for controlling a wireless power transmitter for transmitting charging power to a wireless power receiver. The control method of the present invention comprises the steps of: adjusting the internal impedance of the wireless power transmitter such that the impedance variation occurring when the wireless power receiver is positioned is set to a second impedance variation different from the first impedance variation; applying detection power for detecting the wireless power receiver; detecting the second impedance variation during the application of the detection power so as to detect the wireless power receiver; and changing the impedance variation occurring when the wireless power receiver is positioned from the second impedance variation to the first impedance variation.