A method and apparatus for transmitting ACK/NACK information in a multicarrier-supporting wireless communication system are disclosed. A method for allowing a user equipment to transmit ACK/NACK information in a multicarrier-supporting wireless communication system includes generating individual ACK/NACK information in association with individual codewords received from a base station through N carriers (where N≧2) for use in M downlink subframes (where M≧2), performing, if the sum of numbers of bits of the individual ACK/NACK information exceeds a predetermined payload size and M is not set to 9, spatial bundling to individual ACK/NACK information of (M+C−9) carriers ranging over the M downlink subframes, and transmitting the spatially-bundled ACK/NACK information and the remaining individual ACK/NACK information to the base station through one uplink subframe. C is a total sum of maximum numbers of codewords configured in each of the N carriers for use in one downlink subframe.