A wireless power transmitter and a method of controlling the wireless power transmitter are provided. The wireless power transmitter includes a power supply configured to supply charging power; a power transmitter configured to transmit the charging power to a wireless power receiver; an overcurrent protection circuit configured to change an impedance of the wireless power transmitter; and a controller configured to monitor a current value of an output terminal of the power supply, and connect the overcurrent protection circuit to the power transmitter if the monitored current value is greater than a predetermined threshold.