A mobile station apparatus which communicates with a base station apparatus using a plurality of component carriers, transmits uplink control information to the base station apparatus using a single physical uplink control channel in a plurality of uplink component carriers, regardless of whether or not a plurality of physical uplink control channels is assigned by the base station apparatus and, when each physical uplink shared channel of the plurality of uplink component carriers including a first uplink component carrier on which the uplink control information is transmitted using the physical uplink control channel is assigned in the same subframe by the base station apparatus, transmits the uplink control information to the base station apparatus using the physical uplink shared channel of the first uplink component carrier.