According to one embodiment of the present invention, a method for wirelessly transmitting power by a power transmitter including a plurality of coils comprises the steps of: detecting a second power receiver while transmitting power to a first power receiver; determining at least one primary coil appropriate for transmitting power; determining, by using the determined at least one primary coil, whether the second power receiver supports a shared mode protocol; and when the second power receiver supports the shared mode protocol, transmitting power to the first and second power receivers according to the shared mode protocol, wherein the shared mode protocol may be a protocol which simultaneously manages an information exchange between the power transmitter and a plurality of power receivers.