A method of allocating a paging carrier in a multi-carrier environment is disclosed. The method of allocating the paging carrier includes receiving a first message including first allocation information of the paging carrier, transmitting a second message for requesting entry into an idle mode to a base station; and receiving a third message including second allocation information of a changed paging carrier from the base station. At this time, the paging carrier includes a paging channel out of multiple carriers including one or more carriers.