Disclosed is a control method of a wireless power transmitter, including transmitting power to a plurality of wireless power receivers based on a first power value required by a first wireless power receiver from among the plurality of wireless power receivers, and before reaching a threshold condition in which a system error occurs in the wireless power transmitter, transmitting a power adjust command to reduce the power to a lower percentage of a maximum received power level, to at least one wireless power receiver from among the plurality of wireless power receivers, wherein the power adjust command is a control command for reducing power consumption of the at least one wireless power receiver from among the plurality of wireless power receivers, and wherein the system error comprises at least one of an over-temperature error, an over-current error, and an over-voltage error.