Provided are a base station, a terminal whereby erroneous detection of control information can be reduced to prevent the degradation of the system throughput. A PDCCH generation unit (104) forms a downstream allocation control information unit (i.e., DCI) including cyclic redundant check (CRC) bits, which have been masked or scrambled by use of ID information of a terminal (200), and further including a bit sequence (i.e., virtual CRC) known between the terminal (200) and the base station; and an allocation unit (108) and a multiplex unit (109) map the formed DCI to a resource region (i.e., R-PDCCH region) that can be used as any one of a downstream control channel region and a downstream data channel region. That is, the PDCCH generation unit (104) includes the virtual CRC into the DCI only when the DCI addressed to the terminal (200) is mapped to the R-PDCCH region.