The present specification provides a wireless power transmission device comprising: a power conversion unit configured so as to transmit, in a power transfer phase, wireless power generated on the basis of magnetic coupling to a wireless power receiving device; and a communication/control unit configured so as to perform an initial calibration for a power parameter prior to the power transfer phase, receive, from the wireless power receiving device, a first received power packet indicating the power received by the wireless power receiving device during the power transfer phase, and detect a foreign object by using the received power and a first power loss determined on the basis of the initial calibration.