A method of transmitting, by a transmitter, data in a communication system, the method comprising: encoding an information bit sequence (a) by using a first parity check matrix, consisting of a first systematic part corresponding to the information bit sequence (a) and a first parity part, to generate a first codeword, the first codeword consisting of the information bit sequence (a) and a first parity bit sequence (b) corresponding to the first parity part; transmitting the first codeword to a receiver; and receiving a negative reception acknowledgement (NACK) from the receiver in response to the first codeword, and the method characterized by: encoding a part of the information bit sequence (a p) by using a second parity check matrix consisting of a second systematic part corresponding to the part of the information bit sequence (a p) and a second parity part, to generate a second codeword, the second codeword consisting of the part of the information bit sequence (a p) and a second parity bit sequence (d) corresponding to the second parity part; and transmitting the second parity bit sequence (d) without re-transmitting the part of the information bit sequence (a p)to the receiver, wherein the first parity check matrix is corresponding to a first coding rate, and a part of the second parity check matrix is different from the first parity check matrix, and wherein the second parity check matrix is corresponding to a second coding rate different from the first coding rate, wherein the first parity part of the first parity check matrix is different from the second parity part of the second parity check matrix, and wherein each of the first and second parity check matrixes consists of sub-blocks each of which is a z-by-z zero matrix, a z-by-z identity matrix or a z-by-z permutation matrix generated by shifting each row of the z-by-z identity matrix as much as a shift number. encoding an information bit sequence (a) by using a first parity check matrix, consisting of a first systematic part corresponding to the information bit sequence (a) and a first parity part, to generate a first codeword, the first codeword consisting of the information bit sequence (a) and a first parity bit sequence (b) corresponding to the first parity part; transmitting the first codeword to a receiver; and receiving a negative reception acknowledgement (NACK) from the receiver in response to the first codeword, and the method characterized by: encoding a part of the information bit sequence (a p) by using a second parity check matrix consisting of a second systematic part corresponding to the part of the information bit sequence (a p) and a second parity part, to generate a second codeword, the second codeword consisting of the part of the information bit sequence (a p) and a second parity bit sequence (d) corresponding to the second parity part; and transmitting the second parity bit sequence (d) without re-transmitting the part of the information bit sequence (a p)to the receiver, wherein the first parity check matrix is corresponding to a first coding rate, and a part of the second parity check matrix is different from the first parity check matrix, and wherein the second parity check matrix is corresponding to a second coding rate different from the first coding rate, wherein the first parity part of the first parity check matrix is different from the second parity part of the second parity check matrix, and wherein each of the first and second parity check matrixes consists of sub-blocks each of which is a z-by-z zero matrix, a z-by-z identity matrix or a z-by-z permutation matrix generated by shifting each row of the z-by-z identity matrix as much as a shift number. encoding a part of the information bit sequence (a p) by using a second parity check matrix consisting of a second systematic part corresponding to the part of the information bit sequence (a p) and a second parity part, to generate a second codeword, the second codeword consisting of the part of the information bit sequence (a p) and a second parity bit sequence (d) corresponding to the second parity part; and transmitting the second parity bit sequence (d) without re-transmitting the part of the information bit sequence (a p)to the receiver, wherein the first parity check matrix is corresponding to a first coding rate, and a part of the second parity check matrix is different from the first parity check matrix, and wherein the second parity check matrix is corresponding to a second coding rate different from the first coding rate, wherein the first parity part of the first parity check matrix is different from the second parity part of the second parity check matrix, and wherein each of the first and second parity check matrixes consists of sub-blocks each of which is a z-by-z zero matrix, a z-by-z identity matrix or a z-by-z permutation matrix generated by shifting each row of the z-by-z identity matrix as much as a shift number.