A memory system includes a memory device and a controller. The memory device includes a plurality of non-volatile memory groups individually storing a plurality of data segments, each data segment corresponding to a codeword. The controller is configured to perform hard decision decoding to correct an error when the error is included in a first data segment among the plurality of data segments, determine whether other data segments associated with the first data segment, among the plurality of data segments, are readable when the hard decision decoding fails, and perform chipkill decoding based on the first data segment and the other data segments when the other data segments are readable.