A wireless communication base station apparatus that can raise the usage efficiency of the frequency resources of the whole system in a multicarrier transmission. In this apparatus, a separating part (103) separates symbols received from a modulating part (102) into symbols to be assigned to a first subcarriers group and into symbols to be assigned to a second subcarriers group. A setting part (106-1) sets the transmission power of the symbols, which are to be assigned to the first subcarriers group, to a power value as calculated by a power calculating part (105), while a setting part (106-2) sets the transmission power of the symbols, which are to be assigned to the second subcarriers group, to a power value as calculated by the power calculating part (105). Thus, the transmission power control is differently performed between the symbols to be assigned to the first subcarriers group and the symbols to be assigned to the second subcarriers group.