A base station apparatus comprising: a transmitting unit configured to transmit, to a user equipment, a higher layer signal including first information used for configuring a first set of one or more downlink component carriers and a second set of one or more downlink component carriers, the first set corresponding to a first value of a field of second information, the second set corresponding to a second value of the field of the second information, the second information being used for requesting a transmission of channel state information, wherein the transmitting unit is configured to transmit using a physical downlink control channel, to the user equipment, downlink control information including the second information, the downlink control information being used for scheduling of a physical uplink shared channel in one uplink component carrier; and a receiving unit configured to receive using the physical uplink shared channel, from the user equipment, the channel state information for the first set of the one or more downlink component carriers which is configured in a case that more than one downlink component carrier is configured and the downlink control information including the second information is transmitted and a value of the field of the second information is the first value, wherein the receiving unit is configured to receive using the physical uplink shared channel, from the user equipment, the channel state information for the second set of the one or more downlink component carriers which is configured in a case that more than one downlink component carrier is configured and the downlink control information including the second information is transmitted and a value of the field of the second information is the second value, wherein the downlink control information is mapped on a user equipment specific search space. a transmitting unit configured to transmit, to a user equipment, a higher layer signal including first information used for configuring a first set of one or more downlink component carriers and a second set of one or more downlink component carriers, the first set corresponding to a first value of a field of second information, the second set corresponding to a second value of the field of the second information, the second information being used for requesting a transmission of channel state information, wherein the transmitting unit is configured to transmit using a physical downlink control channel, to the user equipment, downlink control information including the second information, the downlink control information being used for scheduling of a physical uplink shared channel in one uplink component carrier; and a receiving unit configured to receive using the physical uplink shared channel, from the user equipment, the channel state information for the first set of the one or more downlink component carriers which is configured in a case that more than one downlink component carrier is configured and the downlink control information including the second information is transmitted and a value of the field of the second information is the first value, wherein the receiving unit is configured to receive using the physical uplink shared channel, from the user equipment, the channel state information for the second set of the one or more downlink component carriers which is configured in a case that more than one downlink component carrier is configured and the downlink control information including the second information is transmitted and a value of the field of the second information is the second value, wherein the downlink control information is mapped on a user equipment specific search space.