A method of encoding and decoding using an LDPC code is disclosed, by which a memory for storing a parity check matrix necessary for the encoding or decoding using the LDPC code and calculation amount and complexity necessary for the encoding or decoding can be reduced. The present invention includes a step of encoding an input data using a parity check matrix H having a configuration of H=[Hd|Hp] (Hd is (n−k)×k dimensional, Hp is (n−k)×(n−k) dimensional, k is a bit number of the input data, and n is a bit number of a codeword), wherein if the Hd comprises a plurality of sub-matrices, each of the sub-matrices has predetermined regularity in a row or column weight.