Disclosed herein is a method of transmitting uplink control information by a user equipment (UE) in which a plurality of cells are configured including receiving downlink data through at least one of the cells, and piggybacking hybrid automatic repeat and request (HARQ)-acknowledgement (ACK) information about the downlink data on a physical uplink shared channel (PUSCH) and transmitting the same. The HARQ-ACK information may be generated for one cell-group of a plurality of cell-groups configured based on the plurality of cells, and the one cell-group selected for generating the HARQ-ACK information may be indicated through cyclic redundancy check (CRC) attached to the HARQ-ACK information.