In a memory controller for performing error correction decoding, using an iterative decoding scheme, the memory controller includes a variable node update module for allocating the initial LLR values to variable nodes, and updating values of the variable nodes, using the initial LLR values and Check to Variable (C2V) messages corresponding to the variable nodes in an ith iteration, a syndrome checker for performing a syndrome check, using the values of the variable nodes updated in the ith iteration, and a reversal determiner for determining whether to reverse the sign of an initial LLR value of a target variable node based on a ratio of signs of C2V messages corresponding to the target variable node, when the syndrome check corresponding to the ith iteration fails.