A base station apparatus comprising: a control section that assigns resource assignment information about each of a plurality of uplink component bands, to each of control channels allocated to a smaller number of specific downlink component bands than a number of the plurality of uplink component bands for a terminal apparatus; and a generating section that generates control information having the resource assignment information, which is masked with each of terminal IDs respectively configured for the plurality of uplink component bands, characterized by comprising: a configuring section that configures the terminal IDs for the plurality of uplink component bands by creating one or more temporary terminal IDs based on a predetermined terminal ID configured in advance for the terminal apparatus, a number of the one or more temporary IDs being equivalent to a difference between the number of the plurality of uplink component bands and a number of specific downlink component bands, wherein the configuration section creates the temporary terminal IDs by cyclically shifting the predetermined terminal ID by respective relative indexes indicating how far the downlink component bands respectively associated with the plurality of uplink component bands are apart from the specific downlink component band. a control section that assigns resource assignment information about each of a plurality of uplink component bands, to each of control channels allocated to a smaller number of specific downlink component bands than a number of the plurality of uplink component bands for a terminal apparatus; and a generating section that generates control information having the resource assignment information, which is masked with each of terminal IDs respectively configured for the plurality of uplink component bands, characterized by comprising: a configuring section that configures the terminal IDs for the plurality of uplink component bands by creating one or more temporary terminal IDs based on a predetermined terminal ID configured in advance for the terminal apparatus, a number of the one or more temporary IDs being equivalent to a difference between the number of the plurality of uplink component bands and a number of specific downlink component bands, wherein the configuration section creates the temporary terminal IDs by cyclically shifting the predetermined terminal ID by respective relative indexes indicating how far the downlink component bands respectively associated with the plurality of uplink component bands are apart from the specific downlink component band. a configuring section that configures the terminal IDs for the plurality of uplink component bands by creating one or more temporary terminal IDs based on a predetermined terminal ID configured in advance for the terminal apparatus, a number of the one or more temporary IDs being equivalent to a difference between the number of the plurality of uplink component bands and a number of specific downlink component bands, wherein the configuration section creates the temporary terminal IDs by cyclically shifting the predetermined terminal ID by respective relative indexes indicating how far the downlink component bands respectively associated with the plurality of uplink component bands are apart from the specific downlink component band.