A method is presented of reporting control information in a wireless communication system in which M downlink time divisional duplex (TDD) subframes are associated with an uplink TDD subframe. A user equipment (UE), supporting at least one cell including a primary cell, receives a radio resource control (RRC) message indicating resource allocation information used for a first PUCCH format. The UE receives a first physical downlink shared channel (PDSCH) and a second PDSCH in one of the M downlink TDD subframes, wherein the second PDSCH is received with a downlink assignment index (DAI). The UE selects a physical uplink control channel (PUCCH) format among a plurality of PUCCH formats including the first PUCCH format and a second PUCCH format, and transmits a positive-acknowledgement (ACK)/negative-acknowledgement (NACK) signal for the first and second PDSCHs by using the selected PUCCH format.