To enable an uplink control signal subjected to user multiplexing by an orthogonally multiplexing method using the cyclic shift to be user-demultiplexed, and further enable channel estimation accuracy to be improved, a radio communication method of the invention is characterized in that a mobile terminal apparatus provides a plurality of subcarriers with phase rotation amounts set to minimize the number of unit subcarriers for coherent averaging in association with the number of multiplexed users, and transmits an uplink control signal using the plurality of subcarriers provided with the phase rotation amounts, and that a radio base station apparatus receives the uplink control signal, performs coherent averaging on reference signal using the different number of unit subcarriers corresponding to the number of multiplexed users to demultiplex into a reference signal for each of the users, and estimates a channel variation using the demultiplexed reference signal.