An apparatus is provided for decoding a Low-Density Parity Check (LDPC) code in a communication system. In the LDPC decoding apparatus, an edge memory stores a message delivered through an edge between a variable node and a check node. A node memory stores a node value. A node processor performs a node processing operation using information stored in at least one of the node memory and the edge memory, stores a check node value generated by performing the node processing operation in the node memory, and stores a message generated by performing the node processing operation in the edge memory. A switch switches outputs of the node memory and the node processor through a permutation operation. A parity check verifier parity-checks an output from the node memory. A controller provides a control signal for controlling the node processor.