The present invention relates to a wireless communication system. More particularly, the present invention relates to a method for performing processes in which a terminal determines control channel allocation, as well as to an apparatus for the method. The method comprises the following steps: monitoring, on a first carrier, a first search space, containing a control channel candidate set, for control channels having no carrier indication information; and monitoring, on a second carrier, a second search space, containing a control channel candidate set, for control channels having carrier indication information. If the terminal is set to monitor a plurality of control channel candidates which have the same radio network temporary identifier (RNTI), the same information size, and the same first control channel element (CCE) in the first search space and in the second search space, the control channels are received only in the first search space on the first carrier.