Disclosed herein are operation methods of a memory controller which controls a memory device. The method includes storing write data in a first area of the memory device, extracting first error position information indicating a position of at least one error included in data stored in the first area, storing the first error position information in a second area of the memory device, reading read data from the first area of the memory device, reading the first error position information from the second area of the memory device, refining the read data based on the first error position information to generate refined data, performing soft decision decoding based on the refined data to generate corrected data, and outputting the corrected data.