A base station comprising: a transmitting section configured to transmit, to a terminal apparatus, a first physical downlink control channel, PDCCH, and a first physical downlink shared channel, PDSCH, on a first component carrier and to transmit a second PDCCH and a second PDSCH on a second component carrier, the first PDCCH including a first transmission power control, TPC, field, the first PDSCH including first downlink data, the second PDCCH including a second TPC field, and the second PDSCH including second downlink data, a control section configured to allocate, to the first TPC field of the first PDCCH, control information for controlling transmission power of a physical uplink control channel, PUCCH, resource on an uplink component band set in the terminal apparatus, and to allocate, to the second TPC field of the second PDCCH, control information for setting the PUCCH resource in the uplink component band, wherein the first component carrier is associated with the uplink component band set in the terminal apparatus and the second component carrier is a component carrier other than the component carrier associated with the uplink component band set in the terminal apparatus; and a receiving section configured to receive, on the PUCCH resource of the uplink component band set for the terminal apparatus, a response signal for each of the first downlink data and the second downlink data transmitted on the first component carrier and the second component carrier, and to extract the response signal for the first downlink data and the response signal for the second downlink data from the PUCCH resource in the uplink component band based on the control information that the control section allocates to the second TPC field of the second PDCCH. a transmitting section configured to transmit, to a terminal apparatus, a first physical downlink control channel, PDCCH, and a first physical downlink shared channel, PDSCH, on a first component carrier and to transmit a second PDCCH and a second PDSCH on a second component carrier, the first PDCCH including a first transmission power control, TPC, field, the first PDSCH including first downlink data, the second PDCCH including a second TPC field, and the second PDSCH including second downlink data, a control section configured to allocate, to the first TPC field of the first PDCCH, control information for controlling transmission power of a physical uplink control channel, PUCCH, resource on an uplink component band set in the terminal apparatus, and to allocate, to the second TPC field of the second PDCCH, control information for setting the PUCCH resource in the uplink component band, wherein the first component carrier is associated with the uplink component band set in the terminal apparatus and the second component carrier is a component carrier other than the component carrier associated with the uplink component band set in the terminal apparatus; and a receiving section configured to receive, on the PUCCH resource of the uplink component band set for the terminal apparatus, a response signal for each of the first downlink data and the second downlink data transmitted on the first component carrier and the second component carrier, and to extract the response signal for the first downlink data and the response signal for the second downlink data from the PUCCH resource in the uplink component band based on the control information that the control section allocates to the second TPC field of the second PDCCH.