A method of handling a barred cell in a wireless communication system is disclosed. The method of handling a barred cell in a user equipment using a plurality of frequencies includes releasing a Radio Resource Control (RRC) connection between the user equipment and a network if authentication between the user equipment and the network fails, and regarding a cell having a first uplink radio link and a first downlink radio link, a cell having only a second uplink radio link and a cell having only a second downlink radio link as barred cells, if the RRC connection is released.