In a radio communication system using OCC for DMRS, a base station apparatus correctly receives PUSCH. If a first mode is set in which a demodulation reference signal of a physical uplink shared channel is multiplied by an orthogonal code determined in advance or if a temporary C-RNTI was used for a transmission of downlink control information, the demodulation reference signal of the physical uplink shared channel is multiplied by the orthogonal code determined in advance, and if a second mode is set in which the demodulation reference signal of the physical uplink shared channel is multiplied by an orthogonal code determined on the basis of cyclic shift information in the downlink control information and moreover, if an RNTI other than the temporary C-RNTI was used for the transmission of the downlink control information, the demodulation reference signal of the physical uplink shared channel is multiplied by the orthogonal code determined on the basis of the cyclic shift information in the downlink control information.