A disclosed base station in a multi-carrier system performs frequency scheduling in a frequency bandwidth including plural resource blocks each including one or more sub-carriers. The base station includes a frequency scheduler determining scheduling information for allocating one or more resource blocks to a communication terminal having good channel quality based on a channel quality indicator reported from plural of the communication terminals; a unit encoding and modulating a control channel transmitting the scheduling information; a multiplexing unit frequency-division multiplexing the control channel with a channel other than the control channel in accordance with the scheduling information; and a unit transmitting an output signal from the multiplexing unit in the multi-carrier system.