A method for monitoring a control channel in a multiple carrier system, and a user equipment (UE) therefore are discussed. The method according to one embodiment includes, if an aggregation of carriers is configured and if a carrier indicator field (CIF) is configured, monitoring a plurality of downlink control channels within a plurality of UE-specific search spaces of a first carrier; and receiving downlink control information (DCI) on at least one of the plurality of the downlink control channels, which is successfully decoded, via the first carrier. The DCI includes scheduling information on either a downlink channel or an uplink channel in a second carrier.