A controller includes an Error Correction Code (ECC) encoder adding a first parity to data to generate a data set, and encoding the data set to generate a first parity data set, a buffer temporarily storing the first parity data set, an ECC decoder decoding the first parity data set received from the buffer to generate a decoded data set, a first checker performing a Low Density Parity Check (LDPC) encoding on the decoded data set to generate an LDPC data set to which a second parity is added, and a second checker performing a syndrome check operation on the LDCP data set including the first and second parities.