A memory system comprises: a memory cell array suitable for storing first data and a first parity, which is used to correct an error of the first data; and an error correcting circuit suitable for generating second data and a second parity, which includes bits obtained by correcting an error of the first parity and a bit obtained by correcting an error of a second sub-parity; wherein the error correcting circuit includes: a single error correction and double error detection (SECDED) parity generator suitable for generating a second pre-parity, which includes a first sub-parity and the second sub-parity; a syndrome decoder suitable for generating a first parity error flag and a first data error flag by decoding a syndrome; a SEC parity corrector suitable for correcting an error of the first parity based on the first parity error flag; a DED parity error detector suitable for generating a second sub-parity error flag based on an error information of the first data used to generate the second sub-parity; and a DED parity corrector suitable for correcting any error of the second sub-parity based on the second sub-parity error flag.