A method is provided for transmitting a control channel for resource allocation to a terminal by a base station in an Orthogonal Frequency Division Multiple Access (OFDMA) wireless communication system. An additional resource allocation indicator is set indicating whether the number of consecutive resource block sets allocated to a terminal is greater than one. A reference control channel is generated including reference resource allocation information for a first consecutive resource block set and the set additional resource allocation indicator. An additional control channel using additional resource allocation information is generated, when there are one or more additional consecutive resource block sets. At least one of the generated reference control channel and the generated additional control channels is encoded before transmission.