The present invention is related to an apparatus and method for performing communication in a wireless power transfer system. The description discloses a wireless power transmitter including a communication/control unit configured to perform a negotiation for a first available power indicator with a wireless power reception apparatus; and a power conversion unit configured to transmit a wireless power to the wireless power reception apparatus by generating magnetic coupling in a primary coil according to the first available power indicator. The wireless power transmitter provides an effect that a wireless power transmission apparatus is available to obtain status and authority as a master/transmitter depending on a situation, and current ambient situation/environment is reflected in real time.