A method for receiving resources allocated from a base station by a terminal in an OFDMA mobile communication system. The method includes receiving, for a data channel, a number of first components, which indicates an amount of resources used with a first resource allocation scheme, and a number of second components, which indicates an amount of resources used with a second resource allocation scheme, from the base station over a common control channel; determining first and second identifier lengths of channel elements for the first and second resource allocation schemes according to the number of first components and the number of second components; receiving resource allocation information including an identifier indicating at least one channel element allocated to the terminal, over a data control channel using one of the identifier lengths; and transmitting and receiving data over a resource of a channel element indicated by the received identifier.