Provided is a base station device capable of reducing a DL-CSI feedback amount in a TDD type radio communication system in which a DL bandwidth is different from a UL bandwidth. In this device, a demultiplexing unit (133) separates an UL pilot, a DL-CQI, and a DL-CSI fed back from a plurality of UEs as communication partners; a channel estimation unit (134) performs channel sounding by using a UL pilot from a UE in which a DL channel and a UL channel are allocated by overlapping a part of the bandwidth so as to obtain UL-CSI; a control DL-CSI acquisition unit (135) performs interpolation of DL-CSI by using the DL-CSI of some RB contained in the bandwidth where the DL channel and the UL channel fed back from the UE are not overlapped; and a DL close loop control unit (104) combines the estimated UL-CSI and the interpolated DL-CSI so as to use them as DL-CSI for controlling the DL close loop.