A method for encoding data using a Low-Density Parity-Check (LDPC) code comprising the steps of: extracting first column group information, serving as a set of information regarding positions of rows with weight 1, from a reference column in each column group of a first parity-check matrix, wherein the lengths of a codeword and information word of the first parity check matrix are represented by N 1 and K 1, respectively, M 1 and q are two integers satisfying q=(N 1 - K 1)/ M 1, and K 1 is grouped into K 1 /M 1 column groups of M 1 columns; generating second column group information by transforming the first column group information into the second column group information; generating a second parity-check matrix using the second column group information, wherein the lengths of a codeword and information word of the second parity check matrix are represented by N 2 and K 2, respectively, M 2 and q are two integers satisfying q=(N 2 - K 2)/ M 2, K 2 is grouped into K 2 /M 2 column groups of M 2 columns; and N 2 =pN 1, K 2 =pK 1, and M 2 =pM 1, where p is a positive integer; and encoding data using the second parity-check matrix, wherein the generating the second column group information further comprises: generating candidates for a reference column of a column group in the second column group information by shifting the positions of rows with weight 1 from the reference column in each column group of the first parity-check matrix by multiple of column length of the first parity-check matrix, wherein the shifted positions of rows with weight 1 are within a required column length of the second parity-check matrix; and forming the second column group information by selecting one of the candidates which has the best characteristics of cycles on the Tanner graph of the second parity-check matrix, wherein the generating the second parity-check matrix further comprises: generating a first partial matrix corresponding to information word portion using the second column group information; generating a second partial matrix of a dual diagonal shape, corresponding to the parity portion; and generating the second parity-check matrix by combining the first partial matrix and the second partial matrix. extracting first column group information, serving as a set of information regarding positions of rows with weight 1, from a reference column in each column group of a first parity-check matrix, wherein the lengths of a codeword and information word of the first parity check matrix are represented by N 1 and K 1, respectively, M 1 and q are two integers satisfying q=(N 1 - K 1)/ M 1, and K 1 is grouped into K 1 /M 1 column groups of M 1 columns; generating second column group information by transforming the first column group information into the second column group information; generating a second parity-check matrix using the second column group information, wherein the lengths of a codeword and information word of the second parity check matrix are represented by N 2 and K 2, respectively, M 2 and q are two integers satisfying q=(N 2 - K 2)/ M 2, K 2 is grouped into K 2 /M 2 column groups of M 2 columns; and N 2 =pN 1, K 2 =pK 1, and M 2 =pM 1, where p is a positive integer; and encoding data using the second parity-check matrix, generating candidates for a reference column of a column group in the second column group information by shifting the positions of rows with weight 1 from the reference column in each column group of the first parity-check matrix by multiple of column length of the first parity-check matrix, wherein the shifted positions of rows with weight 1 are within a required column length of the second parity-check matrix; and forming the second column group information by selecting one of the candidates which has the best characteristics of cycles on the Tanner graph of the second parity-check matrix, generating a first partial matrix corresponding to information word portion using the second column group information; generating a second partial matrix of a dual diagonal shape, corresponding to the parity portion; and generating the second parity-check matrix by combining the first partial matrix and the second partial matrix.