The present description relates to an apparatus and method for receiving a control channel in a multi-component carrier system. The method for performing random access disclosed in the present description comprises the steps of: transmitting a random access preamble to a base station from an activated sub-serving cell; monitoring physical downlink control channel candidates during a response window one the basis of a certain aggregation in a temporary search space in a control region of the activated sub-serving cell, wherein the control region consists of a group of control channel elements; and adjusting an uplink time of the activated sub-serving cell according to a time advance command indicated by a random access response when the random access response, including a random access identifier corresponding to the random access preamble, is received in the response window.