A decoding device and a decoding method which relate to: receiving a codeword; estimating a number of errors included in the received codeword; and decoding the codeword based on the estimated number of errors using at least one of a first parity check matrix and a second parity check matrix, wherein the first parity check matrix corresponds to a first low-density parity check (LDPC) code, and the second parity check matrix corresponds to a second LDPC code, and wherein the first parity check matrix is based on a first code type, and the second parity check matrix is based on a second code type different from the first code type.