Disclosed herein is a wireless power transmitter for solving a problem that a collision occurs when recognizing an initial wireless power receiver in two-way communication of wireless power transmission. A wireless power transmitter according to a first embodiment disclosed herein may include a transceiver configured to transmit and/or receive a message to and/or from a wireless power receiver; and a controller configured to control the transceiver to transmit a message for requesting identification information to the wireless power receiver, and determine whether the identification information is validly received from the wireless power receiver by the transceiver in response to the identification information request, and control the transceiver to transmit a message for requesting sleep mode switching to the wireless power receiver when the identification information is validly received by the transceiver.