A method for managing power in a transmitter to wirelessly transmit the power to a receiver. The method includes transmitting AC power through a resonance frequency band to the receiver using a transmission resonant coil, transmitting a state information of the transmitter including information related to the number of receivers that can be supported by the transmitter through out-of-band communication having a specific frequency band which is different from the resonance frequency band, receiving a state information of the receiver including information related to a rectified DC power detected by the receiver through rectification of the AC power from the receiver through the out-of-band communication and adjusting the AC power to transmit to the receiver based on the information related to the rectified DC power.