A method and apparatus for controlling uplink transmission power of a wireless communication system is provided. The method for controlling uplink transmission power of a user equipment in a wireless communication system includes aggregating a plurality of uplink carriers into an uplink carrier group by frequency; selecting one of a plurality of downlink carriers associated with at least one of the uplink carriers of the uplink carrier group in terms of path loss; and determining transmission power of the uplink carriers based on the path loss of the selected downlink carrier. The method and apparatus for controlling uplink transmission power according to the present invention is advantageous to minimize the signaling overhead and processing load of the user equipment aggregating multiple carriers in a wireless communication system.