Provided are a method and an apparatus for a user equipment, which is allocated a plurality of serving cells, receiving acknowledgement/negative acknowledgement (ACK/NACK) in a wireless communication system. The method comprises: transmitting uplink data through a physical uplink shared channel (PUSCH); and receiving ACK/NACK with respect to the uplink through a physical hybrid-ARQ indicator channel (PHICH), wherein a serving cell that receives the ACK/NACK is selected from one or more serving cells, which the user equipment monitors to detect an uplink grant that schedules the PUSCH.