Disclosed are a radio transmission device and a radio transmission method which can reduce a processing amount or a memory amount while maintaining the randomizing effect of other cell interference. When using as a reference signal, a ZC sequence of the sequence length uniquely correlated to a transmission bandwidth of a reference signal, as the transmission bandwidth becomes smaller and the sequence length of the ZC sequence becomes shorter, the sequence is switched at a shorter time interval and as the transmission bandwidth becomes greater and the sequence length of the ZC sequence becomes longer, the switching is performed at a longer time interval. Thus, a reference signal is generated by using the ZC sequence in accordance with the timing into which the reference signal transmission bandwidth and the sequence are switched.