1. A method of transmitting an uplink (UL) control signal in a carrier aggregation (CA) system including a plurality of UL component carriers (CCs), the method performed by a user equipment (UE) and comprising:generating uplink control information (UCI) including at least one of an acknowledgement/non-acknowledgement (ACK/NACK) for a hybrid automatic repeat request (HARQ) and a periodic channel state information (CSI);
determining whether a simultaneous transmission of a physical UL control channel (PUCCH) and a physical UL shared channel (PUSCH) is configured;
if the simultaneous transmission of the PUCCH and the PUSCH is not configured, if the UE is not to transmit a PUSCH in a primary CC (PCC) and if the UCI includes at least one of the ACK/NACK and the periodic CSI, selecting one secondary CC (SCC),
wherein the one selected SCC has a lowest CC index among a plurality of SCCs configured by a higher layer signal; and
transmitting the UCI on the PUSCH of the selected SCC.