A method of efficiently allocating a resource to a mobile station to support a real time service in a radio access system is provided. The method includes grouping one or more mobile stations and allocating a group resource area for transmitting bandwidth request information for transmitting real time service data of the grouped one or more mobile stations, and allocating respective individual resource areas of the one or more mobile stations included in the group resource area. Since the method of grouping the mobile service and efficiently allocating an uplink resource are provided, it is possible to reduce message overhead and efficiently use the resource.