A channel encoding apparatus using a parallel concatenated low density parity check (LDPC) code. A first LDPC encoder generates a first component LDPC code according to information bits received. An interleaver interleaves the information bits according to a predetermined interleaving rule. A second LDPC encoder generates a second component LDPC code according to the interleaved information bits. A controller performs a control operation such that the information bits, the first component LDPC code which is first parity bits corresponding to the information bits, and the second component LDPC code which is second parity bits corresponding to the information bits are combined according to a predetermined code rate.