It is possible to provide a radio transmission device and a radio transmission method which can avoid degradation of a channel estimation accuracy using a reference signal formed by a ZC sequence even when the RS transmission band of a local cell is different from that of an adjacent cell. A mobile station decides a cyclic shift sequence corresponding to RB allocation information from an RS table which correlates different frequency bandwidths from a reference point of respective transmission bands to a spectrum start number of the cyclic shift sequence so as to satisfy a particular relationship based on the sequence length and transmits the decided cyclic shift sequence as RS to a base station. The base station uses the same RS table as the RS table of the mobile station and performs correlation calculation of the RS transmitted from the mobile station, thereby performing channel estimation.