Disclosed herein relates to a method and apparatus of establishing a sleep mode operation in a multi-carrier system. The method of establishing a sleep mode operation in a communication system of transmitting and receiving data using a multi-carrier including a primary carrier for transmitting and receiving control information and data and a secondary carrier using a radio frequency (RF) different from the primary carrier may include requesting a sleep mode switching to a base station through the primary carrier and receiving a sleep mode parameter including a sleep mode cycle and a listening window from the base station; entering into a multi-carrier sleep mode having a sleep cycle configured with a listening window capable of transmitting and receiving data and a sleep window incapable of transmitting and receiving data; transmitting a bandwidth request message to a base station through the primary carrier if data traffic to be is transmitted to the base station is generated in the multi-carrier sleep window;changing a sleep mode cycle of the primary carrier to terminate the sleep window of the primary carrier and enter into a listening window; changing a sleep mode cycle of the secondary carrier to be identical to the changed sleep mode cycle of the primary carrier; and transmitting uplink data traffic to the base station during the listening window of the changed sleep mode cycle through the primary carrier and secondary carrier.