1. A method for receiving ACK/NACK information in a wireless access system supporting a carrier aggregation scheme, the method performed by a user equipment (UE) and comprising:receiving a physical downlink control channel (PDCCH) including downlink control information (DCI) from a base station (BS) on a first component carrier (CC), wherein the DCI includes a carrier indicator field (CIF) indicating a second CC and scheduling information;
transmitting, to the BS, uplink data on the second CC indicated by the CIF through a physical uplink shared channel (PUSCH) based on the scheduling information; and
receiving ACK/NACK information for the PUSCH from the BS on the first CC, where the PDCCH has been received,
wherein the first CC and the second CC are included in a plurality of CCs which are assigned to the UE.