Provided is a radio communication base station device which can prevent lowering of use efficiency of a channel communication resource for performing a frequency diversity transmission when simultaneously performing a frequency scheduling transmission and the frequency diversity transmission in a multicarrier communication. In the device, a modulation unit (12) executes a modulation process on Dch data after encoded so as to generate a Dch data symbol. A modulation unit (22) executes a modulation process on the encoded Lch data so as to generate an Lch data symbol. An allocation unit (103) allocates the Dch data symbol and the Lch data symbol to respective sub carriers constituting an OFDM symbol and outputs them to a multiplexing unit (104). Here, when a plurality of Dch are used for a Dch data symbol of one mobile station, the allocation unit (103) uses Dch of continuous channel numbers.