A wireless power transmitter includes a power conversion unit configured to transfer wireless power to a wireless power receiver by using magnetic coupling between the wireless power transmitter and the wireless power receiver; and a communication/control unit configured to control the wireless power and to perform transmission or reception of data based on communication with the wireless power receiver, wherein the communication/control unit receives from the wireless power receiver a received power packet (RPP) informing a value of power received by the wireless power receiver, transmits a bit pattern, in response to the RPP, requesting for transmitting at least one data packet from the wireless power transmitter to the wireless power receiver, receives a response packet from the wireless power receiver in response to the bit pattern, and transmits the at least one data packet to the wireless power receiver.