An encoding apparatus which performs encoding such as Low Density Parity Check (LDPC) encoding is provided. The encoding apparatus includes: an encoder encoding input bits using a parity check matrix including a plurality of blocks, each being formed of a first information word sub-matrix and a first parity sub-matrix arranged next to each other, and a second information sub-matrix and a second parity sub-matrix arranged next to each other; a bit determiner determining a value of a last sub-parity bit among sub-parity bits generated by encoding the input bits with respect to a first block among the plurality of blocks; and a bit modifier reversing values of bits generated by encoding the input bits with respect to a second block next to the first block based on the value of the last parity bit among the sub-parity bits generated by the encoding with respect to the first block.