A base station apparatus which communicates with a mobile station apparatus using a plurality of downlink component carriers and one or more uplink component carriers, the base station apparatus comprising: a transmitting unit configured to transmit, to the mobile station apparatus, a radio resource control signal including first information configuring resources for transmitting channel state information on a physical uplink control channel, the first information indicating which of the uplink component carriers to use for transmitting the channel state information, the transmitting unit being configured to transmit, to the mobile station apparatus, second information on a physical downlink control channel in a downlink component carrier group, the second information indicating resources allocated to a physical uplink shared channel, the downlink component carrier group comprising at least one of the plurality of downlink component carriers; and a receiving unit configured to receive, from the mobile station apparatus, the channel state information on the physical uplink control channel in the uplink component carrier indicated by the first information, the receiving unit being configured to receive, from the mobile station apparatus, uplink data and the channel state information on the physical uplink shared channel in the uplink component carrier indicated by the first information, if the physical uplink shared channel is allocated by the second information on the uplink component carrier indicated by the first information, wherein the transmitting unit is configured to transmit to the mobile station apparatus, a positive acknowledgment or a negative acknowledgment for the reception on the physical uplink shared channel, the positive acknowledgment or the negative acknowledgment being transmitted on a physical hybrid ARQ indicator channel in a same downlink component carrier group as the downlink component carrier group in which the second information is transmitted on the physical downlink control channel. a transmitting unit configured to transmit, to the mobile station apparatus, a radio resource control signal including first information configuring resources for transmitting channel state information on a physical uplink control channel, the first information indicating which of the uplink component carriers to use for transmitting the channel state information, the transmitting unit being configured to transmit, to the mobile station apparatus, second information on a physical downlink control channel in a downlink component carrier group, the second information indicating resources allocated to a physical uplink shared channel, the downlink component carrier group comprising at least one of the plurality of downlink component carriers; and a receiving unit configured to receive, from the mobile station apparatus, the channel state information on the physical uplink control channel in the uplink component carrier indicated by the first information, the receiving unit being configured to receive, from the mobile station apparatus, uplink data and the channel state information on the physical uplink shared channel in the uplink component carrier indicated by the first information, if the physical uplink shared channel is allocated by the second information on the uplink component carrier indicated by the first information, wherein the transmitting unit is configured to transmit to the mobile station apparatus, a positive acknowledgment or a negative acknowledgment for the reception on the physical uplink shared channel, the positive acknowledgment or the negative acknowledgment being transmitted on a physical hybrid ARQ indicator channel in a same downlink component carrier group as the downlink component carrier group in which the second information is transmitted on the physical downlink control channel.