A method for paging in a wireless access system is provided. A method for paging a mobile station of an idle mode includes allocating large paging group identifier and small paging group identifier of a paging group to which the mobile station belongs to a header; allocating a large paging group flag and a small paging group flag to the header, the large paging group flag and the small paging group flag indicating the presence of a paging message for the mobile station; and transmitting the header to the mobile station of the idle mode.