A user terminal carries out radio communication with a plurality of cells by employing carrier aggregation, and has a receiver that, when a connection is established with a TDD cell, receives information about a given DL/UL configuration that is selected from a plurality of DL/UL configurations, and a processor that controls transmission and reception to and from the TDD cell, and a DL/UL configuration to carry out DL communication in all subframes is included as one in the plurality of DL/UL configurations, and the processor uses the DL/UL configuration to carry out DL communication in all subframes as one of the DL/UL configurations only when the connecting TDD cell is a secondary cell. If so, the processor feeds back an A/N in response to each DL subframe of the secondary cell by using a given UL subframe of a primary cell.