WIRELESS CHARGING METHOD AND APPARATUS THEREFOR

A wireless charging method in a wireless power transmitter, the method including sensing an object in a charging region, measuring a quality factor value, receiving information including a reference quality factor value, detecting a foreign object using the measured quality factor value and the reference quality factor value, and transmitting a response signal that includes ACK information or NAK information depending on whether or not the foreign object is detected. Further, the wireless power transmitter transmits information including a first guaranteed power value when the response signal includes the ACK information, and transmits information including a second guaranteed power value when the response signal includes the NAK information, and the first guaranteed power value is greater than the second guaranteed power value.