A method of encoding/decoding using an LDPC code and apparatus thereof are disclosed, by which a memory for storing a parity check matrix can be saved. The present invention includes generating a parity check matrix by expanding a base matrix including a permutation type defining a permutation matrix as at least one element, wherein the permutation matrix is generated from permutating a sequence of at least one of rows and columns of at least one base permutation matrix or rotating the at least one base permutation matrix and encoding or decoding the input data using the parity check matrix.