Provided are a base station and a transmission method whereby, even in a case where a cross carrier scheduling is employed, the increase in the number of blind decodings on a PDCCH receiving side can be suppressed without need of signaling of an upper layer at the time of changing PDCCH CC. In the base station (100), a CC setting unit (101) sets, from among a plurality of downstream unit carriers included in a UE CC set, a control channel unit carrier (PDCCH CC) used for transmitting allocation information related to a data transmission resource of each downstream unit carrier included in the UE CC set.