A method for controlling a joining power receiver (200-2) by a registered power receiver (200-1), the method comprising: receiving (S306), by the registered power receiver (200-1), power information from the joining power receiver (200-2) while the registered power receiver (200-1) receives second power from a wireless power transmitter , wherein the power information indicates an amount of first power required by the joining power receiver (200-2); identifying, by the registered power receiver (200-1), a remaining transmission capacity of the wireless power transmitter , while the registered power receiver (200-1) receives the second power from the wireless power transmitter ; determining (S310), by the registered power receiver (200-1), whether the first power can be supplied to the joining power receiver (200-2), based on the amount of the first power required by the joining power receiver (200-2) and the remaining transmission capacity of the wireless power transmitter ; and if the first power cannot be supplied to the joining power receiver (200-2), transmitting (S312), by the registered power receiver (200-1) to the joining power receiver (200-2), a first signal for requesting the joining power receiver (200-2) to suspend performing charging until the joining power receiver (200-2) receives a second signal for requesting the joining power receiver (200-2) to start charging; wherein determining whether the first power can be supplied to the joining power receiver (200-2) comprises: if the remaining transmission capacity of the wireless power transmitter after transmitting the first power to the joining power receiver (200-2) would be smaller than a preset reference value, determining that the first power cannot be supplied to the joining power receiver (200-2). receiving (S306), by the registered power receiver (200-1), power information from the joining power receiver (200-2) while the registered power receiver (200-1) receives second power from a wireless power transmitter , wherein the power information indicates an amount of first power required by the joining power receiver (200-2); identifying, by the registered power receiver (200-1), a remaining transmission capacity of the wireless power transmitter , while the registered power receiver (200-1) receives the second power from the wireless power transmitter ; determining (S310), by the registered power receiver (200-1), whether the first power can be supplied to the joining power receiver (200-2), based on the amount of the first power required by the joining power receiver (200-2) and the remaining transmission capacity of the wireless power transmitter ; and if the first power cannot be supplied to the joining power receiver (200-2), transmitting (S312), by the registered power receiver (200-1) to the joining power receiver (200-2), a first signal for requesting the joining power receiver (200-2) to suspend performing charging until the joining power receiver (200-2) receives a second signal for requesting the joining power receiver (200-2) to start charging; wherein determining whether the first power can be supplied to the joining power receiver (200-2) comprises: if the remaining transmission capacity of the wireless power transmitter after transmitting the first power to the joining power receiver (200-2) would be smaller than a preset reference value, determining that the first power cannot be supplied to the joining power receiver (200-2). <EOS>