It is an object to provide a wireless communication base station device that can prevent the decline of a system throughput due to the degradation of a utilization efficiency of a communication resource of a channel for carrying out a frequency diversity transmission when a frequency scheduling transmission and a frequency diversity transmission are concurrently carried out in multiple carrier communication. In the wireless communication base station device, a modulation unit (12) carries out modulation processing for Dch data after coding to generate a Dch data symbol. A modulation unit (22) carries out modulation processing for Lch data after coding to generate an Lch data symbol. An allocation unit (103) allocates the Dch data symbol and Lch data symbol to each sub-carrier composing an OFDM symbol and outputs the allocated sub-carrier to a multiplex unit (104). In this case, the allocation unit (103) allocates the Dch data symbol to a plurality of resource blocks where one Dch is arranged at an interval equal to integral multiples of the number of resource blocks composing a resource block group.