A wireless power transmitter includes: a power transmitting coil configured to receive alternating current (AC) power applied thereto and wirelessly transmit the AC power; a sensing device configured to output one or more sensing signals having magnitudes that are variable based on an approach of an object; and a circuitry configured to determine whether an acknowledgement signal has been received from a wireless power receiver and whether a foreign object has entered a region of the wireless power transmitter based on a change in the magnitudes of the one or more sensing signals, and configured to control transmission of the AC power through the power transmitting coil based on a result of the determining of whether the acknowledgement signal has been received from the wireless power receiver and whether the foreign object has entered the region of the wireless power transmitter.