Provided is a method and apparatus for operating an idle mode in a wireless communication system. The method includes receiving a first message requesting entry to an idle mode from a Subscriber Station (SS) through at least one Base Station (BS), selecting in response to reception of the first message whether the MS is to enter an idle mode in which BSs belonging to a paging group broadcast a paging message for the MS or whether the MS is to enter a semi-idle mode in which BSs belonging to a semi-idle paging group, which is a subset of the paging group, broadcast the paging message for the SS, and transmitting Paging announce information instructing the BSs belonging to the semi-idle paging group to broadcast the paging message for the SS, if the semi-idle mode is selected.