Provided is a radio communication station device which can prevent limiting of resource allocation in a UE group. The radio communication device includes: a CCE allocation unit (104); modulation units (103-1 to 103-K); an arrangement unit (108); and a radio transmission unit (111). The CCE allocation unit (104) allocates allocation information allocated to a PDCCH which is inputted from the modulation unit (103-1 to 103-K) as follows. Among a plurality of search spaces shared by a greater number of UE groups as the CCE aggregation size of the PDCCH increases, a particular search space corresponding to the CCE aggregation size of the PDCCH and a mobile group (UE group) of the PDCCH is selected as a space to which the allocation information is to be allocated. The arrangement unit (108) arranges the allocation information in a downlink resource corresponding to the CCE of the particular search space allocated among the downlink resources secured for the PDCCH. The radio transmission unit (111) transmits an OFDM symbol having the allocation information from an antenna (112) to a mobile station.