A wireless power transmitter and receiver using an in-band communication and a method thereof are provided. In one embodiment, a wireless power transmitter using an in-band communication may include: a source resonance unit including a source resonator that is configured to transmit wireless power to one or more in-band resonators; a source controller configured to control a resonance frequency and an impedance of the source resonator, to detect an in-band resonator located in a location corresponding to a wireless power receiver among the in-band resonators, and to generate a control signal of the detected in-band resonator; and an in-band resonance unit configured to receive and demodulate identification information associated with the wireless power receiver via the one or more in-band resonators, and to transmit the wireless power and transmission data via the in-band resonator corresponding to the wireless power receiver.