A wireless power transfer system includes a plurality of power sources and at least one power receiver, in which power transfer from the power sources to the power receiver is performed in wireless by using magnetic field resonance or electric field resonance. In the system, one of the plurality of power sources is designated as a master power source and the other one or more power sources are designated as slave power sources. In addition, the master power source controls the plurality of power sources and the at least one power receiver to perform the power transfer. This allows the system to perform the power transfer in an optimum state.