A wireless communication system comprising a base station device and a mobile station device, wherein the base station device and the mobile station device are configured to communicate with each other, and the mobile station device is configured to generate a first ACK/NACK sequence and a second ACK/NACK sequence from ACKs/NACKs for transport blocks, the transport blocks being received from the base station device, first ACK/NACKs in the first ACK/NACK sequence being different from second ACK/NACKs in the second ACK/NACK sequence, encode the first ACK/NACK sequence to generate a first coded bit sequence, and encode the second ACK/NACK sequence to generate a second coded bit sequence, the first ACK/NACK sequence and the second ACK/NACK sequence being separately encoded by using a same set of base sequences, concatenate the first coded bit sequence and the second coded bit sequence differently based on whether the ACKs/NACKs are to be transmitted on a physical uplink control channel or on a physical uplink shared channel, wherein a first number of bits being the length of the first coded bit sequence and a second number of bits being the length of the second coded bit sequence are separately calculated in a case that a physical uplink shared channel resource is allocated and the ACKs/NACKs are to be transmitted on the physical uplink shared channel, the first number and the second number are predefined values in a case that a physical uplink shared channel resource is not allocated and the ACKs/NACKs are to be transmitted on the physical uplink control channel, and the base station device is configured to perform a reception and a decoding process of the ACKs/NACKs. the base station device and the mobile station device are configured to communicate with each other, and the mobile station device is configured to generate a first ACK/NACK sequence and a second ACK/NACK sequence from ACKs/NACKs for transport blocks, the transport blocks being received from the base station device, first ACK/NACKs in the first ACK/NACK sequence being different from second ACK/NACKs in the second ACK/NACK sequence, encode the first ACK/NACK sequence to generate a first coded bit sequence, and encode the second ACK/NACK sequence to generate a second coded bit sequence, the first ACK/NACK sequence and the second ACK/NACK sequence being separately encoded by using a same set of base sequences, concatenate the first coded bit sequence and the second coded bit sequence differently based on whether the ACKs/NACKs are to be transmitted on a physical uplink control channel or on a physical uplink shared channel, wherein a first number of bits being the length of the first coded bit sequence and a second number of bits being the length of the second coded bit sequence are separately calculated in a case that a physical uplink shared channel resource is allocated and the ACKs/NACKs are to be transmitted on the physical uplink shared channel, the first number and the second number are predefined values in a case that a physical uplink shared channel resource is not allocated and the ACKs/NACKs are to be transmitted on the physical uplink control channel, and the base station device is configured to perform a reception and a decoding process of the ACKs/NACKs.