A method for detecting a foreign object between a transmission pad and a reception pad for wireless power transfer (WPT) may comprise: performing, by a processor, a zero phase angle (ZPA) control for a power transfer converter included in or connected to the transmission pad; detecting, by the processor, a phase difference between an input current and an input voltage of the power transfer converter; and determining, by the processor, whether or not the foreign object exists between the transmission pad and the reception pad by comparing the phase difference with a reference value.